1 | // https://github.com/rbehrends/vspace |
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2 | #include "vspace.h" |
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3 | #include "kernel/mod2.h" |
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4 | #ifdef HAVE_VSPACE |
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5 | #ifdef HAVE_CPP_THREADS |
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6 | #include <thread> |
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7 | #endif |
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8 | #include <cstddef> |
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9 | |
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10 | #if defined(__GNUC__) && (__GNUC__<9) &&!defined(__clang__) |
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11 | |
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12 | namespace vspace { |
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13 | namespace internals { |
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14 | |
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15 | size_t config[4] |
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16 | = { METABLOCK_SIZE, MAX_PROCESS, SEGMENT_SIZE, MAX_SEGMENTS }; |
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17 | |
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18 | VMem VMem::vmem_global; |
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19 | |
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20 | // offsetof() only works for POD types, so we need to construct |
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21 | // a portable version of it for metapage fields. |
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22 | |
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23 | #define metapageaddr(field) \ |
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24 | ((char *) &vmem.metapage->field - (char *) vmem.metapage) |
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25 | |
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26 | size_t VMem::filesize() { |
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27 | struct stat stat; |
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28 | fstat(fd, &stat); |
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29 | return stat.st_size; |
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30 | } |
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31 | |
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32 | Status VMem::init(int fd) { |
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33 | this->fd = fd; |
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34 | for (int i = 0; i < MAX_SEGMENTS; i++) |
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35 | segments[i] = VSeg(NULL); |
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36 | for (int i = 0; i < MAX_PROCESS; i++) { |
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37 | int channel[2]; |
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38 | if (pipe(channel) < 0) { |
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39 | for (int j = 0; j < i; j++) { |
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40 | close(channels[j].fd_read); |
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41 | close(channels[j].fd_write); |
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42 | } |
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43 | return Status(ErrOS); |
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44 | } |
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45 | channels[i].fd_read = channel[0]; |
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46 | channels[i].fd_write = channel[1]; |
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47 | } |
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48 | lock_metapage(); |
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49 | init_metapage(filesize() == 0); |
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50 | unlock_metapage(); |
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51 | freelist = metapage->freelist; |
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52 | return Status(ErrNone); |
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53 | } |
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54 | |
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55 | Status VMem::init() { |
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56 | FILE *fp = tmpfile(); |
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57 | Status result = init(fileno(fp)); |
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58 | if (!result.ok()) |
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59 | return result; |
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60 | current_process = 0; |
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61 | file_handle = fp; |
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62 | metapage->process_info[0].pid = getpid(); |
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63 | return Status(ErrNone); |
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64 | } |
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65 | |
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66 | Status VMem::init(const char *path) { |
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67 | int fd = open(path, O_RDWR | O_CREAT, 0600); |
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68 | if (fd < 0) |
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69 | return Status(ErrFile); |
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70 | init(fd); |
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71 | lock_metapage(); |
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72 | // TODO: enter process in meta table |
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73 | unlock_metapage(); |
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74 | return Status(ErrNone); |
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75 | } |
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76 | |
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77 | void VMem::deinit() { |
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78 | if (file_handle) { |
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79 | fclose(file_handle); |
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80 | file_handle = NULL; |
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81 | } else { |
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82 | close(fd); |
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83 | } |
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84 | munmap(metapage, METABLOCK_SIZE); |
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85 | metapage = NULL; |
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86 | current_process = -1; |
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87 | freelist = NULL; |
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88 | for (int i = 0; i < MAX_SEGMENTS; i++) { |
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89 | if (segments[i].base) munmap(segments[i].base, SEGMENT_SIZE); |
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90 | segments[i] = NULL; |
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91 | } |
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92 | for (int i = 0; i < MAX_PROCESS; i++) { |
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93 | close(channels[i].fd_read); |
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94 | close(channels[i].fd_write); |
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95 | } |
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96 | } |
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97 | |
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98 | void *VMem::mmap_segment(int seg) { |
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99 | lock_metapage(); |
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100 | void *map = mmap(NULL, SEGMENT_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED, fd, |
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101 | METABLOCK_SIZE + seg * SEGMENT_SIZE); |
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102 | if (map == MAP_FAILED) { |
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103 | // This is an "impossible to proceed from here, because system state |
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104 | // is impossible to proceed from" situation, so we abort the program. |
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105 | perror("mmap"); |
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106 | abort(); |
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107 | } |
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108 | unlock_metapage(); |
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109 | return map; |
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110 | } |
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111 | |
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112 | void VMem::add_segment() { |
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113 | int seg = metapage->segment_count++; |
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114 | ftruncate(fd, METABLOCK_SIZE + metapage->segment_count * SEGMENT_SIZE); |
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115 | void *map_addr = mmap_segment(seg); |
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116 | segments[seg] = VSeg(map_addr); |
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117 | Block *top = block_ptr(seg * SEGMENT_SIZE); |
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118 | top->next = freelist[LOG2_SEGMENT_SIZE]; |
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119 | top->prev = VADDR_NULL; |
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120 | freelist[LOG2_SEGMENT_SIZE] = seg * SEGMENT_SIZE; |
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121 | } |
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122 | |
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123 | void FastLock::lock() { |
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124 | #ifdef HAVE_CPP_THREADS |
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125 | while (_lock.test_and_set()) { |
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126 | } |
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127 | bool empty = _owner < 0; |
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128 | if (empty) { |
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129 | _owner = vmem.current_process; |
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130 | } else { |
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131 | int p = vmem.current_process; |
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132 | vmem.metapage->process_info[p].next = -1; |
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133 | if (_head < 0) |
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134 | _head = p; |
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135 | else |
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136 | vmem.metapage->process_info[_tail].next = p; |
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137 | _tail = p; |
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138 | } |
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139 | _lock.clear(); |
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140 | if (!empty) |
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141 | wait_signal(false); |
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142 | #else |
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143 | lock_file(vmem.fd, _offset); |
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144 | #endif |
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145 | } |
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146 | |
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147 | void FastLock::unlock() { |
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148 | #ifdef HAVE_CPP_THREADS |
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149 | while (_lock.test_and_set()) { |
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150 | } |
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151 | _owner = _head; |
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152 | if (_owner >= 0) |
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153 | _head = vmem.metapage->process_info[_head].next; |
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154 | _lock.clear(); |
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155 | if (_owner >= 0) |
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156 | send_signal(_owner, 0, false); |
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157 | #else |
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158 | unlock_file(vmem.fd, _offset); |
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159 | #endif |
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160 | } |
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161 | |
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162 | static void lock_allocator() { |
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163 | vmem.metapage->allocator_lock.lock(); |
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164 | } |
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165 | |
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166 | static void unlock_allocator() { |
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167 | vmem.metapage->allocator_lock.unlock(); |
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168 | } |
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169 | |
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170 | static void print_freelists() { |
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171 | for (int i = 0; i <= LOG2_SEGMENT_SIZE; i++) { |
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172 | vaddr_t vaddr = vmem.freelist[i]; |
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173 | if (vaddr != VADDR_NULL) { |
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174 | printf("%2d: %ld", i, vaddr); |
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175 | vaddr_t prev = block_ptr(vaddr)->prev; |
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176 | if (prev != VADDR_NULL) { |
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177 | printf("(%ld)", prev); |
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178 | } |
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179 | assert(block_ptr(vaddr)->prev == VADDR_NULL); |
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180 | for (;;) { |
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181 | vaddr_t last_vaddr = vaddr; |
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182 | Block *block = block_ptr(vaddr); |
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183 | vaddr = block->next; |
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184 | if (vaddr == VADDR_NULL) |
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185 | break; |
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186 | printf(" -> %ld", vaddr); |
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187 | vaddr_t prev = block_ptr(vaddr)->prev; |
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188 | if (prev != last_vaddr) { |
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189 | printf("(%ld)", prev); |
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190 | } |
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191 | } |
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192 | printf("\n"); |
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193 | } |
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194 | } |
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195 | fflush(stdout); |
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196 | } |
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197 | |
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198 | void vmem_free(vaddr_t vaddr) { |
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199 | lock_allocator(); |
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200 | vaddr -= offsetof(Block, data); |
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201 | vmem.ensure_is_mapped(vaddr); |
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202 | size_t segno = vmem.segment_no(vaddr); |
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203 | VSeg seg = vmem.segment(vaddr); |
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204 | segaddr_t addr = vmem.segaddr(vaddr); |
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205 | int level = seg.block_ptr(addr)->level(); |
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206 | assert(!seg.is_free(addr)); |
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207 | while (level < LOG2_SEGMENT_SIZE) { |
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208 | segaddr_t buddy = find_buddy(addr, level); |
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209 | Block *block = seg.block_ptr(buddy); |
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210 | // is buddy free and at the same level? |
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211 | if (!block->is_free() || block->level() != level) |
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212 | break; |
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213 | // remove buddy from freelist. |
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214 | Block *prev = vmem.block_ptr(block->prev); |
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215 | Block *next = vmem.block_ptr(block->next); |
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216 | block->data[0] = level; |
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217 | if (prev) { |
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218 | assert(prev->next == vmem.vaddr(segno, buddy)); |
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219 | prev->next = block->next; |
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220 | } else { |
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221 | // head of freelist. |
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222 | assert(vmem.freelist[level] == vmem.vaddr(segno, buddy)); |
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223 | vmem.freelist[level] = block->next; |
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224 | } |
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225 | if (next) { |
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226 | assert(next->prev == vmem.vaddr(segno, buddy)); |
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227 | next->prev = block->prev; |
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228 | } |
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229 | // coalesce block with buddy |
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230 | level++; |
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231 | if (buddy < addr) |
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232 | addr = buddy; |
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233 | } |
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234 | // Add coalesced block to free list |
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235 | Block *block = seg.block_ptr(addr); |
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236 | block->prev = VADDR_NULL; |
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237 | block->next = vmem.freelist[level]; |
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238 | block->mark_as_free(level); |
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239 | vaddr_t blockaddr = vmem.vaddr(segno, addr); |
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240 | if (block->next != VADDR_NULL) |
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241 | vmem.block_ptr(block->next)->prev = blockaddr; |
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242 | vmem.freelist[level] = blockaddr; |
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243 | unlock_allocator(); |
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244 | } |
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245 | |
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246 | vaddr_t vmem_alloc(size_t size) { |
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247 | lock_allocator(); |
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248 | size_t alloc_size = size + offsetof(Block, data); |
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249 | int level = find_level(alloc_size); |
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250 | int flevel = level; |
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251 | while (flevel < LOG2_SEGMENT_SIZE && vmem.freelist[flevel] == VADDR_NULL) |
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252 | flevel++; |
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253 | if (vmem.freelist[flevel] == VADDR_NULL) { |
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254 | vmem.add_segment(); |
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255 | } |
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256 | vmem.ensure_is_mapped(vmem.freelist[flevel]); |
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257 | while (flevel > level) { |
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258 | // get and split a block |
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259 | vaddr_t blockaddr = vmem.freelist[flevel]; |
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260 | assert((blockaddr & ((1 << flevel) - 1)) == 0); |
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261 | Block *block = vmem.block_ptr(blockaddr); |
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262 | vmem.freelist[flevel] = block->next; |
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263 | if (vmem.freelist[flevel] != VADDR_NULL) |
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264 | vmem.block_ptr(vmem.freelist[flevel])->prev = VADDR_NULL; |
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265 | vaddr_t blockaddr2 = blockaddr + (1 << (flevel - 1)); |
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266 | Block *block2 = vmem.block_ptr(blockaddr2); |
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267 | flevel--; |
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268 | block2->next = vmem.freelist[flevel]; |
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269 | block2->prev = blockaddr; |
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270 | block->next = blockaddr2; |
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271 | block->prev = VADDR_NULL; |
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272 | // block->prev == VADDR_NULL already. |
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273 | vmem.freelist[flevel] = blockaddr; |
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274 | } |
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275 | assert(vmem.freelist[level] != VADDR_NULL); |
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276 | Block *block = vmem.block_ptr(vmem.freelist[level]); |
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277 | vaddr_t vaddr = vmem.freelist[level]; |
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278 | vaddr_t result = vaddr + offsetof(Block, data); |
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279 | vmem.freelist[level] = block->next; |
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280 | if (block->next != VADDR_NULL) |
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281 | vmem.block_ptr(block->next)->prev = VADDR_NULL; |
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282 | block->mark_as_allocated(vaddr, level); |
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283 | unlock_allocator(); |
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284 | memset(block->data, 0, size); |
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285 | return result; |
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286 | } |
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287 | |
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288 | void init_flock_struct( |
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289 | struct flock &lock_info, size_t offset, size_t len, bool lock) { |
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290 | lock_info.l_start = offset; |
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291 | lock_info.l_len = len; |
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292 | lock_info.l_pid = 0; |
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293 | lock_info.l_type = lock ? F_WRLCK : F_UNLCK; |
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294 | lock_info.l_whence = SEEK_SET; |
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295 | } |
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296 | |
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297 | void lock_file(int fd, size_t offset, size_t len) { |
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298 | struct flock lock_info; |
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299 | init_flock_struct(lock_info, offset, len, true); |
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300 | fcntl(fd, F_SETLKW, &lock_info); |
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301 | } |
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302 | |
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303 | void unlock_file(int fd, size_t offset, size_t len) { |
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304 | struct flock lock_info; |
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305 | init_flock_struct(lock_info, offset, len, false); |
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306 | fcntl(fd, F_SETLKW, &lock_info); |
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307 | } |
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308 | |
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309 | void lock_metapage() { |
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310 | lock_file(vmem.fd, 0); |
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311 | } |
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312 | |
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313 | void unlock_metapage() { |
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314 | unlock_file(vmem.fd, 0); |
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315 | } |
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316 | |
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317 | void init_metapage(bool create) { |
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318 | if (create) |
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319 | ftruncate(vmem.fd, METABLOCK_SIZE); |
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320 | vmem.metapage = (MetaPage *) mmap( |
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321 | NULL, METABLOCK_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED, vmem.fd, 0); |
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322 | if (create) { |
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323 | memcpy(vmem.metapage->config_header, config, sizeof(config)); |
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324 | for (int i = 0; i <= LOG2_SEGMENT_SIZE; i++) { |
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325 | vmem.metapage->freelist[i] = VADDR_NULL; |
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326 | } |
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327 | vmem.metapage->segment_count = 0; |
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328 | vmem.metapage->allocator_lock = FastLock(metapageaddr(allocator_lock)); |
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329 | } else { |
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330 | assert(memcmp(vmem.metapage->config_header, config, sizeof(config)) != 0); |
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331 | } |
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332 | } |
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333 | |
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334 | static void lock_process(int processno) { |
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335 | lock_file(vmem.fd, |
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336 | metapageaddr(process_info) |
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337 | + sizeof(ProcessInfo) * vmem.current_process); |
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338 | } |
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339 | |
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340 | static void unlock_process(int processno) { |
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341 | unlock_file(vmem.fd, |
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342 | metapageaddr(process_info) |
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343 | + sizeof(ProcessInfo) * vmem.current_process); |
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344 | } |
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345 | |
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346 | static ProcessInfo &process_info(int processno) { |
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347 | return vmem.metapage->process_info[processno]; |
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348 | } |
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349 | |
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350 | bool send_signal(int processno, ipc_signal_t sig, bool lock) { |
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351 | if (lock) |
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352 | lock_process(processno); |
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353 | if (process_info(processno).sigstate != Waiting) { |
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354 | unlock_process(processno); |
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355 | return false; |
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356 | } |
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357 | if (processno == vmem.current_process) { |
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358 | process_info(processno).sigstate = Accepted; |
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359 | process_info(processno).signal = sig; |
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360 | } else { |
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361 | process_info(processno).sigstate = Pending; |
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362 | process_info(processno).signal = sig; |
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363 | int fd = vmem.channels[processno].fd_write; |
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364 | char buf[1] = { 0 }; |
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365 | while (write(fd, buf, 1) != 1) { |
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366 | } |
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367 | } |
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368 | if (lock) |
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369 | unlock_process(processno); |
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370 | return true; |
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371 | } |
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372 | |
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373 | ipc_signal_t check_signal(bool resume, bool lock) { |
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374 | ipc_signal_t result; |
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375 | if (lock) |
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376 | lock_process(vmem.current_process); |
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377 | SignalState sigstate = process_info(vmem.current_process).sigstate; |
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378 | switch (sigstate) { |
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379 | case Waiting: |
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380 | case Pending: { |
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381 | int fd = vmem.channels[vmem.current_process].fd_read; |
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382 | char buf[1]; |
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383 | if (lock && sigstate == Waiting) { |
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384 | unlock_process(vmem.current_process); |
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385 | while (read(fd, buf, 1) != 1) { |
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386 | } |
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387 | lock_process(vmem.current_process); |
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388 | } else { |
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389 | while (read(fd, buf, 1) != 1) { |
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390 | } |
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391 | } |
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392 | result = process_info(vmem.current_process).signal; |
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393 | process_info(vmem.current_process).sigstate |
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394 | = resume ? Waiting : Accepted; |
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395 | if (lock) |
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396 | unlock_process(vmem.current_process); |
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397 | break; |
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398 | } |
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399 | case Accepted: |
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400 | result = process_info(vmem.current_process).signal; |
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401 | if (resume) |
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402 | process_info(vmem.current_process).sigstate = Waiting; |
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403 | if (lock) |
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404 | unlock_process(vmem.current_process); |
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405 | break; |
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406 | } |
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407 | return result; |
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408 | } |
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409 | |
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410 | void accept_signals() { |
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411 | lock_process(vmem.current_process); |
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412 | process_info(vmem.current_process).sigstate = Waiting; |
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413 | unlock_process(vmem.current_process); |
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414 | } |
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415 | |
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416 | ipc_signal_t wait_signal(bool lock) { |
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417 | return check_signal(true, lock); |
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418 | } |
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419 | |
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420 | } // namespace internals |
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421 | |
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422 | pid_t fork_process() { |
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423 | using namespace internals; |
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424 | lock_metapage(); |
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425 | for (int p = 0; p < MAX_PROCESS; p++) { |
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426 | if (vmem.metapage->process_info[p].pid == 0) { |
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427 | pid_t pid = fork(); |
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428 | if (pid < 0) { |
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429 | // error |
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430 | return -1; |
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431 | } else if (pid == 0) { |
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432 | // child process |
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433 | int parent = vmem.current_process; |
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434 | vmem.current_process = p; |
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435 | lock_metapage(); |
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436 | vmem.metapage->process_info[p].pid = getpid(); |
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437 | unlock_metapage(); |
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438 | send_signal(parent); |
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439 | } else { |
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440 | // parent process |
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441 | unlock_metapage(); |
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442 | wait_signal(); |
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443 | // child has unlocked metapage, so we don't need to. |
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444 | } |
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445 | return pid; |
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446 | } |
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447 | } |
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448 | unlock_metapage(); |
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449 | return -1; |
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450 | } |
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451 | |
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452 | void Semaphore::post() { |
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453 | int wakeup = -1; |
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454 | internals::ipc_signal_t sig; |
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455 | _lock.lock(); |
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456 | if (_head == _tail) { |
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457 | _value++; |
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458 | } else { |
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459 | // don't increment value, as we'll pass that on to the next process. |
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460 | wakeup = _waiting[_head]; |
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461 | sig = _signals[_head]; |
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462 | next(_head); |
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463 | } |
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464 | _lock.unlock(); |
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465 | if (wakeup >= 0) { |
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466 | internals::send_signal(wakeup, sig); |
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467 | } |
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468 | } |
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469 | |
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470 | bool Semaphore::try_wait() { |
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471 | bool result = false; |
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472 | _lock.lock(); |
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473 | if (_value > 0) { |
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474 | _value--; |
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475 | result = true; |
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476 | } |
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477 | _lock.unlock(); |
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478 | return result; |
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479 | } |
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480 | |
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481 | void Semaphore::wait() { |
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482 | _lock.lock(); |
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483 | if (_value > 0) { |
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484 | _value--; |
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485 | _lock.unlock(); |
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486 | return; |
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487 | } |
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488 | _waiting[_tail] = internals::vmem.current_process; |
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489 | _signals[_tail] = 0; |
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490 | next(_tail); |
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491 | _lock.unlock(); |
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492 | internals::wait_signal(); |
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493 | } |
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494 | |
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495 | bool Semaphore::start_wait(internals::ipc_signal_t sig) { |
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496 | _lock.lock(); |
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497 | if (_value > 0) { |
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498 | if (internals::send_signal(internals::vmem.current_process, sig)) |
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499 | _value--; |
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500 | _lock.unlock(); |
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501 | return false; |
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502 | } |
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503 | _waiting[_tail] = internals::vmem.current_process; |
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504 | _signals[_tail] = sig; |
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505 | next(_tail); |
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506 | _lock.unlock(); |
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507 | return true; |
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508 | } |
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509 | |
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510 | bool Semaphore::stop_wait() { |
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511 | bool result = false; |
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512 | _lock.lock(); |
---|
513 | for (int i = _head; i != _tail; next(i)) { |
---|
514 | if (_waiting[i] == internals::vmem.current_process) { |
---|
515 | int last = i; |
---|
516 | next(i); |
---|
517 | while (i != _tail) { |
---|
518 | _waiting[last] = _waiting[i]; |
---|
519 | _signals[last] = _signals[i]; |
---|
520 | last = i; |
---|
521 | next(i); |
---|
522 | } |
---|
523 | _tail = last; |
---|
524 | result = true; |
---|
525 | break; |
---|
526 | } |
---|
527 | } |
---|
528 | _lock.unlock(); |
---|
529 | return result; |
---|
530 | } |
---|
531 | |
---|
532 | void EventSet::add(Event *event) { |
---|
533 | event->_next = NULL; |
---|
534 | if (_head == NULL) { |
---|
535 | _head = _tail = event; |
---|
536 | } else { |
---|
537 | _tail->_next = event; |
---|
538 | _tail = event; |
---|
539 | } |
---|
540 | } |
---|
541 | |
---|
542 | int EventSet::wait() { |
---|
543 | size_t n = 0; |
---|
544 | for (Event *event = _head; event; event = event->_next) { |
---|
545 | if (!event->start_listen((int) (n++))) { |
---|
546 | break; |
---|
547 | } |
---|
548 | } |
---|
549 | internals::ipc_signal_t result = internals::check_signal(); |
---|
550 | for (Event *event = _head; event; event = event->_next) { |
---|
551 | event->stop_listen(); |
---|
552 | } |
---|
553 | internals::accept_signals(); |
---|
554 | return (int) result; |
---|
555 | } |
---|
556 | |
---|
557 | } // namespace vspace |
---|
558 | #else |
---|
559 | #include <cstdlib> |
---|
560 | #include <unistd.h> |
---|
561 | #include <sys/mman.h> |
---|
562 | #include <sys/stat.h> |
---|
563 | |
---|
564 | |
---|
565 | namespace vspace { |
---|
566 | namespace internals { |
---|
567 | |
---|
568 | size_t config[4] |
---|
569 | = { METABLOCK_SIZE, MAX_PROCESS, SEGMENT_SIZE, MAX_SEGMENTS }; |
---|
570 | |
---|
571 | VMem VMem::vmem_global; |
---|
572 | |
---|
573 | // offsetof() only works for POD types, so we need to construct |
---|
574 | // a portable version of it for metapage fields. |
---|
575 | |
---|
576 | #define metapageaddr(field) \ |
---|
577 | ((char *) &vmem.metapage->field - (char *) vmem.metapage) |
---|
578 | |
---|
579 | size_t VMem::filesize() { |
---|
580 | struct stat stat; |
---|
581 | fstat(fd, &stat); |
---|
582 | return stat.st_size; |
---|
583 | } |
---|
584 | |
---|
585 | Status VMem::init(int fd) { |
---|
586 | this->fd = fd; |
---|
587 | for (int i = 0; i < MAX_SEGMENTS; i++) |
---|
588 | segments[i] = VSeg(NULL); |
---|
589 | for (int i = 0; i < MAX_PROCESS; i++) { |
---|
590 | int channel[2]; |
---|
591 | if (pipe(channel) < 0) { |
---|
592 | for (int j = 0; j < i; j++) { |
---|
593 | close(channels[j].fd_read); |
---|
594 | close(channels[j].fd_write); |
---|
595 | } |
---|
596 | return Status(ErrOS); |
---|
597 | } |
---|
598 | channels[i].fd_read = channel[0]; |
---|
599 | channels[i].fd_write = channel[1]; |
---|
600 | } |
---|
601 | lock_metapage(); |
---|
602 | init_metapage(filesize() == 0); |
---|
603 | unlock_metapage(); |
---|
604 | freelist = metapage->freelist; |
---|
605 | return Status(ErrNone); |
---|
606 | } |
---|
607 | |
---|
608 | Status VMem::init() { |
---|
609 | FILE *fp = tmpfile(); |
---|
610 | Status result = init(fileno(fp)); |
---|
611 | if (!result.ok()) |
---|
612 | return result; |
---|
613 | current_process = 0; |
---|
614 | file_handle = fp; |
---|
615 | metapage->process_info[0].pid = getpid(); |
---|
616 | return Status(ErrNone); |
---|
617 | } |
---|
618 | |
---|
619 | Status VMem::init(const char *path) { |
---|
620 | int fd = open(path, O_RDWR | O_CREAT, 0600); |
---|
621 | if (fd < 0) |
---|
622 | return Status(ErrFile); |
---|
623 | init(fd); |
---|
624 | lock_metapage(); |
---|
625 | // TODO: enter process in meta table |
---|
626 | unlock_metapage(); |
---|
627 | return Status(ErrNone); |
---|
628 | } |
---|
629 | |
---|
630 | void VMem::deinit() { |
---|
631 | if (file_handle) { |
---|
632 | fclose(file_handle); |
---|
633 | file_handle = NULL; |
---|
634 | } else { |
---|
635 | close(fd); |
---|
636 | } |
---|
637 | munmap(metapage, METABLOCK_SIZE); |
---|
638 | metapage = NULL; |
---|
639 | current_process = -1; |
---|
640 | freelist = NULL; |
---|
641 | for (int i = 0; i < MAX_SEGMENTS; i++) { |
---|
642 | if (!segments[i].is_free()) |
---|
643 | munmap(segments[i].base, SEGMENT_SIZE); |
---|
644 | segments[i] = VSeg(NULL); |
---|
645 | } |
---|
646 | for (int i = 0; i < MAX_PROCESS; i++) { |
---|
647 | close(channels[i].fd_read); |
---|
648 | close(channels[i].fd_write); |
---|
649 | } |
---|
650 | } |
---|
651 | |
---|
652 | void *VMem::mmap_segment(int seg) { |
---|
653 | lock_metapage(); |
---|
654 | void *map = mmap(NULL, SEGMENT_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED, fd, |
---|
655 | METABLOCK_SIZE + seg * SEGMENT_SIZE); |
---|
656 | if (map == MAP_FAILED) { |
---|
657 | // This is an "impossible to proceed from here, because system state |
---|
658 | // is impossible to proceed from" situation, so we abort the program. |
---|
659 | perror("mmap"); |
---|
660 | abort(); |
---|
661 | } |
---|
662 | unlock_metapage(); |
---|
663 | return map; |
---|
664 | } |
---|
665 | |
---|
666 | void VMem::add_segment() { |
---|
667 | int seg = metapage->segment_count++; |
---|
668 | ftruncate(fd, METABLOCK_SIZE + metapage->segment_count * SEGMENT_SIZE); |
---|
669 | void *map_addr = mmap_segment(seg); |
---|
670 | segments[seg] = VSeg(map_addr); |
---|
671 | Block *top = block_ptr(seg * SEGMENT_SIZE); |
---|
672 | top->next = freelist[LOG2_SEGMENT_SIZE]; |
---|
673 | top->prev = VADDR_NULL; |
---|
674 | freelist[LOG2_SEGMENT_SIZE] = seg * SEGMENT_SIZE; |
---|
675 | } |
---|
676 | |
---|
677 | void FastLock::lock() { |
---|
678 | #ifdef HAVE_CPP_THREADS |
---|
679 | while (_lock.test_and_set()) { |
---|
680 | } |
---|
681 | bool empty = _owner < 0; |
---|
682 | if (empty) { |
---|
683 | _owner = vmem.current_process; |
---|
684 | } else { |
---|
685 | int p = vmem.current_process; |
---|
686 | vmem.metapage->process_info[p].next = -1; |
---|
687 | if (_head < 0) |
---|
688 | _head = p; |
---|
689 | else |
---|
690 | vmem.metapage->process_info[_tail].next = p; |
---|
691 | _tail = p; |
---|
692 | } |
---|
693 | _lock.clear(); |
---|
694 | if (!empty) |
---|
695 | wait_signal(false); |
---|
696 | #else |
---|
697 | lock_file(vmem.fd, _offset); |
---|
698 | #endif |
---|
699 | } |
---|
700 | |
---|
701 | void FastLock::unlock() { |
---|
702 | #ifdef HAVE_CPP_THREADS |
---|
703 | while (_lock.test_and_set()) { |
---|
704 | } |
---|
705 | _owner = _head; |
---|
706 | if (_owner >= 0) |
---|
707 | _head = vmem.metapage->process_info[_head].next; |
---|
708 | _lock.clear(); |
---|
709 | if (_owner >= 0) |
---|
710 | send_signal(_owner, 0, false); |
---|
711 | #else |
---|
712 | unlock_file(vmem.fd, _offset); |
---|
713 | #endif |
---|
714 | } |
---|
715 | |
---|
716 | static void lock_allocator() { |
---|
717 | vmem.metapage->allocator_lock.lock(); |
---|
718 | } |
---|
719 | |
---|
720 | static void unlock_allocator() { |
---|
721 | vmem.metapage->allocator_lock.unlock(); |
---|
722 | } |
---|
723 | |
---|
724 | static void print_freelists() { |
---|
725 | for (int i = 0; i <= LOG2_SEGMENT_SIZE; i++) { |
---|
726 | vaddr_t vaddr = vmem.freelist[i]; |
---|
727 | if (vaddr != VADDR_NULL) { |
---|
728 | std::printf("%2d: %ld", i, vaddr); |
---|
729 | vaddr_t prev = block_ptr(vaddr)->prev; |
---|
730 | if (prev != VADDR_NULL) { |
---|
731 | std::printf("(%ld)", prev); |
---|
732 | } |
---|
733 | assert(block_ptr(vaddr)->prev == VADDR_NULL); |
---|
734 | for (;;) { |
---|
735 | vaddr_t last_vaddr = vaddr; |
---|
736 | Block *block = block_ptr(vaddr); |
---|
737 | vaddr = block->next; |
---|
738 | if (vaddr == VADDR_NULL) |
---|
739 | break; |
---|
740 | std::printf(" -> %ld", vaddr); |
---|
741 | vaddr_t prev = block_ptr(vaddr)->prev; |
---|
742 | if (prev != last_vaddr) { |
---|
743 | std::printf("(%ld)", prev); |
---|
744 | } |
---|
745 | } |
---|
746 | std::printf("\n"); |
---|
747 | } |
---|
748 | } |
---|
749 | std::fflush(stdout); |
---|
750 | } |
---|
751 | |
---|
752 | void vmem_free(vaddr_t vaddr) { |
---|
753 | lock_allocator(); |
---|
754 | vaddr -= offsetof(Block, data); |
---|
755 | vmem.ensure_is_mapped(vaddr); |
---|
756 | size_t segno = vmem.segment_no(vaddr); |
---|
757 | VSeg seg = vmem.segment(vaddr); |
---|
758 | segaddr_t addr = vmem.segaddr(vaddr); |
---|
759 | int level = seg.block_ptr(addr)->level(); |
---|
760 | assert(!seg.is_free(addr)); |
---|
761 | while (level < LOG2_SEGMENT_SIZE) { |
---|
762 | segaddr_t buddy = find_buddy(addr, level); |
---|
763 | Block *block = seg.block_ptr(buddy); |
---|
764 | // is buddy free and at the same level? |
---|
765 | if (!block->is_free() || block->level() != level) |
---|
766 | break; |
---|
767 | // remove buddy from freelist. |
---|
768 | Block *prev = vmem.block_ptr(block->prev); |
---|
769 | Block *next = vmem.block_ptr(block->next); |
---|
770 | block->data[0] = level; |
---|
771 | if (prev) { |
---|
772 | assert(prev->next == vmem.vaddr(segno, buddy)); |
---|
773 | prev->next = block->next; |
---|
774 | } else { |
---|
775 | // head of freelist. |
---|
776 | assert(vmem.freelist[level] == vmem.vaddr(segno, buddy)); |
---|
777 | vmem.freelist[level] = block->next; |
---|
778 | } |
---|
779 | if (next) { |
---|
780 | assert(next->prev == vmem.vaddr(segno, buddy)); |
---|
781 | next->prev = block->prev; |
---|
782 | } |
---|
783 | // coalesce block with buddy |
---|
784 | level++; |
---|
785 | if (buddy < addr) |
---|
786 | addr = buddy; |
---|
787 | } |
---|
788 | // Add coalesced block to free list |
---|
789 | Block *block = seg.block_ptr(addr); |
---|
790 | block->prev = VADDR_NULL; |
---|
791 | block->next = vmem.freelist[level]; |
---|
792 | block->mark_as_free(level); |
---|
793 | vaddr_t blockaddr = vmem.vaddr(segno, addr); |
---|
794 | if (block->next != VADDR_NULL) |
---|
795 | vmem.block_ptr(block->next)->prev = blockaddr; |
---|
796 | vmem.freelist[level] = blockaddr; |
---|
797 | unlock_allocator(); |
---|
798 | } |
---|
799 | |
---|
800 | vaddr_t vmem_alloc(size_t size) { |
---|
801 | lock_allocator(); |
---|
802 | size_t alloc_size = size + offsetof(Block, data); |
---|
803 | int level = find_level(alloc_size); |
---|
804 | int flevel = level; |
---|
805 | while (flevel < LOG2_SEGMENT_SIZE && vmem.freelist[flevel] == VADDR_NULL) |
---|
806 | flevel++; |
---|
807 | if (vmem.freelist[flevel] == VADDR_NULL) { |
---|
808 | vmem.add_segment(); |
---|
809 | } |
---|
810 | vmem.ensure_is_mapped(vmem.freelist[flevel]); |
---|
811 | while (flevel > level) { |
---|
812 | // get and split a block |
---|
813 | vaddr_t blockaddr = vmem.freelist[flevel]; |
---|
814 | assert((blockaddr & ((1 << flevel) - 1)) == 0); |
---|
815 | Block *block = vmem.block_ptr(blockaddr); |
---|
816 | vmem.freelist[flevel] = block->next; |
---|
817 | if (vmem.freelist[flevel] != VADDR_NULL) |
---|
818 | vmem.block_ptr(vmem.freelist[flevel])->prev = VADDR_NULL; |
---|
819 | vaddr_t blockaddr2 = blockaddr + (1 << (flevel - 1)); |
---|
820 | Block *block2 = vmem.block_ptr(blockaddr2); |
---|
821 | flevel--; |
---|
822 | block2->next = vmem.freelist[flevel]; |
---|
823 | block2->prev = blockaddr; |
---|
824 | block->next = blockaddr2; |
---|
825 | block->prev = VADDR_NULL; |
---|
826 | // block->prev == VADDR_NULL already. |
---|
827 | vmem.freelist[flevel] = blockaddr; |
---|
828 | } |
---|
829 | assert(vmem.freelist[level] != VADDR_NULL); |
---|
830 | Block *block = vmem.block_ptr(vmem.freelist[level]); |
---|
831 | vaddr_t vaddr = vmem.freelist[level]; |
---|
832 | vaddr_t result = vaddr + offsetof(Block, data); |
---|
833 | vmem.freelist[level] = block->next; |
---|
834 | if (block->next != VADDR_NULL) |
---|
835 | vmem.block_ptr(block->next)->prev = VADDR_NULL; |
---|
836 | block->mark_as_allocated(vaddr, level); |
---|
837 | unlock_allocator(); |
---|
838 | memset(block->data, 0, size); |
---|
839 | return result; |
---|
840 | } |
---|
841 | |
---|
842 | void init_flock_struct( |
---|
843 | struct flock &lock_info, size_t offset, size_t len, bool lock) { |
---|
844 | lock_info.l_start = offset; |
---|
845 | lock_info.l_len = len; |
---|
846 | lock_info.l_pid = 0; |
---|
847 | lock_info.l_type = lock ? F_WRLCK : F_UNLCK; |
---|
848 | lock_info.l_whence = SEEK_SET; |
---|
849 | } |
---|
850 | |
---|
851 | void lock_file(int fd, size_t offset, size_t len) { |
---|
852 | struct flock lock_info; |
---|
853 | init_flock_struct(lock_info, offset, len, true); |
---|
854 | fcntl(fd, F_SETLKW, &lock_info); |
---|
855 | } |
---|
856 | |
---|
857 | void unlock_file(int fd, size_t offset, size_t len) { |
---|
858 | struct flock lock_info; |
---|
859 | init_flock_struct(lock_info, offset, len, false); |
---|
860 | fcntl(fd, F_SETLKW, &lock_info); |
---|
861 | } |
---|
862 | |
---|
863 | void lock_metapage() { |
---|
864 | lock_file(vmem.fd, 0); |
---|
865 | } |
---|
866 | |
---|
867 | void unlock_metapage() { |
---|
868 | unlock_file(vmem.fd, 0); |
---|
869 | } |
---|
870 | |
---|
871 | void init_metapage(bool create) { |
---|
872 | if (create) |
---|
873 | ftruncate(vmem.fd, METABLOCK_SIZE); |
---|
874 | vmem.metapage = (MetaPage *) mmap( |
---|
875 | NULL, METABLOCK_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED, vmem.fd, 0); |
---|
876 | if (create) { |
---|
877 | std::memcpy(vmem.metapage->config_header, config, sizeof(config)); |
---|
878 | for (int i = 0; i <= LOG2_SEGMENT_SIZE; i++) { |
---|
879 | vmem.metapage->freelist[i] = VADDR_NULL; |
---|
880 | } |
---|
881 | vmem.metapage->segment_count = 0; |
---|
882 | vmem.metapage->allocator_lock = FastLock(metapageaddr(allocator_lock)); |
---|
883 | } else { |
---|
884 | assert(std::memcmp(vmem.metapage->config_header, config, |
---|
885 | sizeof(config)) != 0); |
---|
886 | } |
---|
887 | } |
---|
888 | |
---|
889 | static void lock_process(int processno) { |
---|
890 | lock_file(vmem.fd, |
---|
891 | metapageaddr(process_info) |
---|
892 | + sizeof(ProcessInfo) * vmem.current_process); |
---|
893 | } |
---|
894 | |
---|
895 | static void unlock_process(int processno) { |
---|
896 | unlock_file(vmem.fd, |
---|
897 | metapageaddr(process_info) |
---|
898 | + sizeof(ProcessInfo) * vmem.current_process); |
---|
899 | } |
---|
900 | |
---|
901 | static ProcessInfo &process_info(int processno) { |
---|
902 | return vmem.metapage->process_info[processno]; |
---|
903 | } |
---|
904 | |
---|
905 | bool send_signal(int processno, ipc_signal_t sig, bool lock) { |
---|
906 | if (lock) |
---|
907 | lock_process(processno); |
---|
908 | if (process_info(processno).sigstate != Waiting) { |
---|
909 | unlock_process(processno); |
---|
910 | return false; |
---|
911 | } |
---|
912 | if (processno == vmem.current_process) { |
---|
913 | process_info(processno).sigstate = Accepted; |
---|
914 | process_info(processno).signal = sig; |
---|
915 | } else { |
---|
916 | process_info(processno).sigstate = Pending; |
---|
917 | process_info(processno).signal = sig; |
---|
918 | int fd = vmem.channels[processno].fd_write; |
---|
919 | char buf[1] = { 0 }; |
---|
920 | while (write(fd, buf, 1) != 1) { |
---|
921 | } |
---|
922 | } |
---|
923 | if (lock) |
---|
924 | unlock_process(processno); |
---|
925 | return true; |
---|
926 | } |
---|
927 | |
---|
928 | ipc_signal_t check_signal(bool resume, bool lock) { |
---|
929 | ipc_signal_t result; |
---|
930 | if (lock) |
---|
931 | lock_process(vmem.current_process); |
---|
932 | SignalState sigstate = process_info(vmem.current_process).sigstate; |
---|
933 | switch (sigstate) { |
---|
934 | case Waiting: |
---|
935 | case Pending: { |
---|
936 | int fd = vmem.channels[vmem.current_process].fd_read; |
---|
937 | char buf[1]; |
---|
938 | if (lock && sigstate == Waiting) { |
---|
939 | unlock_process(vmem.current_process); |
---|
940 | while (read(fd, buf, 1) != 1) { |
---|
941 | } |
---|
942 | lock_process(vmem.current_process); |
---|
943 | } else { |
---|
944 | while (read(fd, buf, 1) != 1) { |
---|
945 | } |
---|
946 | } |
---|
947 | result = process_info(vmem.current_process).signal; |
---|
948 | process_info(vmem.current_process).sigstate |
---|
949 | = resume ? Waiting : Accepted; |
---|
950 | if (lock) |
---|
951 | unlock_process(vmem.current_process); |
---|
952 | break; |
---|
953 | } |
---|
954 | case Accepted: |
---|
955 | result = process_info(vmem.current_process).signal; |
---|
956 | if (resume) |
---|
957 | process_info(vmem.current_process).sigstate = Waiting; |
---|
958 | if (lock) |
---|
959 | unlock_process(vmem.current_process); |
---|
960 | break; |
---|
961 | } |
---|
962 | return result; |
---|
963 | } |
---|
964 | |
---|
965 | void accept_signals() { |
---|
966 | lock_process(vmem.current_process); |
---|
967 | process_info(vmem.current_process).sigstate = Waiting; |
---|
968 | unlock_process(vmem.current_process); |
---|
969 | } |
---|
970 | |
---|
971 | ipc_signal_t wait_signal(bool lock) { |
---|
972 | return check_signal(true, lock); |
---|
973 | } |
---|
974 | |
---|
975 | } // namespace internals |
---|
976 | |
---|
977 | pid_t fork_process() { |
---|
978 | using namespace internals; |
---|
979 | lock_metapage(); |
---|
980 | for (int p = 0; p < MAX_PROCESS; p++) { |
---|
981 | if (vmem.metapage->process_info[p].pid == 0) { |
---|
982 | pid_t pid = fork(); |
---|
983 | if (pid < 0) { |
---|
984 | // error |
---|
985 | return -1; |
---|
986 | } else if (pid == 0) { |
---|
987 | // child process |
---|
988 | int parent = vmem.current_process; |
---|
989 | vmem.current_process = p; |
---|
990 | lock_metapage(); |
---|
991 | vmem.metapage->process_info[p].pid = getpid(); |
---|
992 | unlock_metapage(); |
---|
993 | send_signal(parent); |
---|
994 | } else { |
---|
995 | // parent process |
---|
996 | unlock_metapage(); |
---|
997 | wait_signal(); |
---|
998 | // child has unlocked metapage, so we don't need to. |
---|
999 | } |
---|
1000 | return pid; |
---|
1001 | } |
---|
1002 | } |
---|
1003 | unlock_metapage(); |
---|
1004 | return -1; |
---|
1005 | } |
---|
1006 | |
---|
1007 | void Semaphore::post() { |
---|
1008 | int wakeup = -1; |
---|
1009 | internals::ipc_signal_t sig; |
---|
1010 | _lock.lock(); |
---|
1011 | if (_head == _tail) { |
---|
1012 | _value++; |
---|
1013 | } else { |
---|
1014 | // don't increment value, as we'll pass that on to the next process. |
---|
1015 | wakeup = _waiting[_head]; |
---|
1016 | sig = _signals[_head]; |
---|
1017 | next(_head); |
---|
1018 | } |
---|
1019 | _lock.unlock(); |
---|
1020 | if (wakeup >= 0) { |
---|
1021 | internals::send_signal(wakeup, sig); |
---|
1022 | } |
---|
1023 | } |
---|
1024 | |
---|
1025 | bool Semaphore::try_wait() { |
---|
1026 | bool result = false; |
---|
1027 | _lock.lock(); |
---|
1028 | if (_value > 0) { |
---|
1029 | _value--; |
---|
1030 | result = true; |
---|
1031 | } |
---|
1032 | _lock.unlock(); |
---|
1033 | return result; |
---|
1034 | } |
---|
1035 | |
---|
1036 | void Semaphore::wait() { |
---|
1037 | _lock.lock(); |
---|
1038 | if (_value > 0) { |
---|
1039 | _value--; |
---|
1040 | _lock.unlock(); |
---|
1041 | return; |
---|
1042 | } |
---|
1043 | _waiting[_tail] = internals::vmem.current_process; |
---|
1044 | _signals[_tail] = 0; |
---|
1045 | next(_tail); |
---|
1046 | _lock.unlock(); |
---|
1047 | internals::wait_signal(); |
---|
1048 | } |
---|
1049 | |
---|
1050 | bool Semaphore::start_wait(internals::ipc_signal_t sig) { |
---|
1051 | _lock.lock(); |
---|
1052 | if (_value > 0) { |
---|
1053 | if (internals::send_signal(internals::vmem.current_process, sig)) |
---|
1054 | _value--; |
---|
1055 | _lock.unlock(); |
---|
1056 | return false; |
---|
1057 | } |
---|
1058 | _waiting[_tail] = internals::vmem.current_process; |
---|
1059 | _signals[_tail] = sig; |
---|
1060 | next(_tail); |
---|
1061 | _lock.unlock(); |
---|
1062 | return true; |
---|
1063 | } |
---|
1064 | |
---|
1065 | bool Semaphore::stop_wait() { |
---|
1066 | bool result = false; |
---|
1067 | _lock.lock(); |
---|
1068 | for (int i = _head; i != _tail; next(i)) { |
---|
1069 | if (_waiting[i] == internals::vmem.current_process) { |
---|
1070 | int last = i; |
---|
1071 | next(i); |
---|
1072 | while (i != _tail) { |
---|
1073 | _waiting[last] = _waiting[i]; |
---|
1074 | _signals[last] = _signals[i]; |
---|
1075 | last = i; |
---|
1076 | next(i); |
---|
1077 | } |
---|
1078 | _tail = last; |
---|
1079 | result = true; |
---|
1080 | break; |
---|
1081 | } |
---|
1082 | } |
---|
1083 | _lock.unlock(); |
---|
1084 | return result; |
---|
1085 | } |
---|
1086 | |
---|
1087 | void EventSet::add(Event *event) { |
---|
1088 | event->_next = NULL; |
---|
1089 | if (_head == NULL) { |
---|
1090 | _head = _tail = event; |
---|
1091 | } else { |
---|
1092 | _tail->_next = event; |
---|
1093 | _tail = event; |
---|
1094 | } |
---|
1095 | } |
---|
1096 | |
---|
1097 | int EventSet::wait() { |
---|
1098 | size_t n = 0; |
---|
1099 | for (Event *event = _head; event; event = event->_next) { |
---|
1100 | if (!event->start_listen((int) (n++))) { |
---|
1101 | break; |
---|
1102 | } |
---|
1103 | } |
---|
1104 | internals::ipc_signal_t result = internals::check_signal(); |
---|
1105 | for (Event *event = _head; event; event = event->_next) { |
---|
1106 | event->stop_listen(); |
---|
1107 | } |
---|
1108 | internals::accept_signals(); |
---|
1109 | return (int) result; |
---|
1110 | } |
---|
1111 | |
---|
1112 | } // namespace vspace |
---|
1113 | #endif |
---|
1114 | #endif |
---|