diff options
author | Roberto Ierusalimschy <roberto@inf.puc-rio.br> | 2018-07-25 11:44:46 -0300 |
---|---|---|
committer | Roberto Ierusalimschy <roberto@inf.puc-rio.br> | 2018-07-25 11:44:46 -0300 |
commit | e885dee5ab4dbee2457ee2023340e848fdabdef9 (patch) | |
tree | 1b9a4ac5a9a4d62edfcb99d5fc2416794dcef174 /liolib.c | |
parent | ccae0f5aad11b448fa630a41b2c7c54e69d134d8 (diff) | |
download | lua-e885dee5ab4dbee2457ee2023340e848fdabdef9.tar.gz lua-e885dee5ab4dbee2457ee2023340e848fdabdef9.tar.bz2 lua-e885dee5ab4dbee2457ee2023340e848fdabdef9.zip |
File operations try an "emergency collection" when failing
If a file operation fails do to lack of resources (too many open
files or not enough memory), it does a full garbage collection and
tries the operation again. Lack of resources are "too many open
files" (process wise and system wise) and "not enough memory".
The code is full of '#if's because error codes are not part
of the standard ISO C.
Diffstat (limited to 'liolib.c')
-rw-r--r-- | liolib.c | 68 |
1 files changed, 64 insertions, 4 deletions
@@ -1,5 +1,5 @@ | |||
1 | /* | 1 | /* |
2 | ** $Id: liolib.c,v 2.155 2018/02/21 13:48:44 roberto Exp roberto $ | 2 | ** $Id: liolib.c $ |
3 | ** Standard I/O (and system) library | 3 | ** Standard I/O (and system) library |
4 | ** See Copyright Notice in lua.h | 4 | ** See Copyright Notice in lua.h |
5 | */ | 5 | */ |
@@ -68,7 +68,7 @@ static int l_checkmode (const char *mode) { | |||
68 | 68 | ||
69 | /* ISO C definitions */ | 69 | /* ISO C definitions */ |
70 | #define l_popen(L,c,m) \ | 70 | #define l_popen(L,c,m) \ |
71 | ((void)((void)c, m), \ | 71 | ((void)c, (void)m, \ |
72 | luaL_error(L, "'popen' not supported"), \ | 72 | luaL_error(L, "'popen' not supported"), \ |
73 | (FILE*)0) | 73 | (FILE*)0) |
74 | #define l_pclose(L,file) ((void)L, (void)file, -1) | 74 | #define l_pclose(L,file) ((void)L, (void)file, -1) |
@@ -133,6 +133,51 @@ static int l_checkmode (const char *mode) { | |||
133 | /* }====================================================== */ | 133 | /* }====================================================== */ |
134 | 134 | ||
135 | 135 | ||
136 | /* | ||
137 | ** {====================================================== | ||
138 | ** 'resourcetryagain' | ||
139 | ** This function uses 'errno' to check whether the last error was | ||
140 | ** related to lack of resources (e.g., not enough memory or too many | ||
141 | ** open files). If so, the function performs a full garbage collection | ||
142 | ** to try to release resources, and then it returns 1 to signal to | ||
143 | ** the caller that it is worth trying again the failed operation. | ||
144 | ** Otherwise, it returns 0. Because error codes are not ANSI C, the | ||
145 | ** code must handle any combination of error codes that are defined. | ||
146 | ** ======================================================= | ||
147 | */ | ||
148 | |||
149 | static int resourcetryagain (lua_State *L) { | ||
150 | |||
151 | /* these are the resource-related errors in Linux */ | ||
152 | #if defined(EMFILE) || defined(ENFILE) || defined(ENOMEM) | ||
153 | |||
154 | #if !defined(EMFILE) /* too many open files in the process */ | ||
155 | #define EMFILE -1 /* if not defined, use an impossible value */ | ||
156 | #endif | ||
157 | |||
158 | #if !defined(ENFILE) /* too many open files in the system */ | ||
159 | #define ENFILE -1 | ||
160 | #endif | ||
161 | |||
162 | #if !defined(ENOMEM) /* not enough memory */ | ||
163 | #define ENOMEM -1 | ||
164 | #endif | ||
165 | |||
166 | if (errno == EMFILE || errno == ENFILE || errno == ENOMEM) { | ||
167 | lua_gc(L, LUA_GCCOLLECT); /* try to release resources with a full GC */ | ||
168 | return 1; /* signal to try again the creation */ | ||
169 | } | ||
170 | |||
171 | #endif | ||
172 | |||
173 | return 0; /* else, asume errors are not due to lack of resources */ | ||
174 | |||
175 | } | ||
176 | |||
177 | /* }====================================================== */ | ||
178 | |||
179 | |||
180 | |||
136 | #define IO_PREFIX "_IO_" | 181 | #define IO_PREFIX "_IO_" |
137 | #define IOPREF_LEN (sizeof(IO_PREFIX)/sizeof(char) - 1) | 182 | #define IOPREF_LEN (sizeof(IO_PREFIX)/sizeof(char) - 1) |
138 | #define IO_INPUT (IO_PREFIX "input") | 183 | #define IO_INPUT (IO_PREFIX "input") |
@@ -245,9 +290,22 @@ static LStream *newfile (lua_State *L) { | |||
245 | } | 290 | } |
246 | 291 | ||
247 | 292 | ||
293 | /* | ||
294 | ** Equivalent to 'fopen', but if it fails due to a lack of resources | ||
295 | ** (see 'resourcetryagain'), do an "emergency" garbage collection to try | ||
296 | ** to close some files and then tries to open the file again. | ||
297 | */ | ||
298 | static FILE *trytoopen (lua_State *L, const char *path, const char *mode) { | ||
299 | FILE *f = fopen(path, mode); | ||
300 | if (f == NULL && resourcetryagain(L)) /* resource failure? */ | ||
301 | f = fopen(path, mode); /* try to open again */ | ||
302 | return f; | ||
303 | } | ||
304 | |||
305 | |||
248 | static void opencheck (lua_State *L, const char *fname, const char *mode) { | 306 | static void opencheck (lua_State *L, const char *fname, const char *mode) { |
249 | LStream *p = newfile(L); | 307 | LStream *p = newfile(L); |
250 | p->f = fopen(fname, mode); | 308 | p->f = trytoopen(L, fname, mode); |
251 | if (p->f == NULL) | 309 | if (p->f == NULL) |
252 | luaL_error(L, "cannot open file '%s' (%s)", fname, strerror(errno)); | 310 | luaL_error(L, "cannot open file '%s' (%s)", fname, strerror(errno)); |
253 | } | 311 | } |
@@ -259,7 +317,7 @@ static int io_open (lua_State *L) { | |||
259 | LStream *p = newfile(L); | 317 | LStream *p = newfile(L); |
260 | const char *md = mode; /* to traverse/check mode */ | 318 | const char *md = mode; /* to traverse/check mode */ |
261 | luaL_argcheck(L, l_checkmode(md), 2, "invalid mode"); | 319 | luaL_argcheck(L, l_checkmode(md), 2, "invalid mode"); |
262 | p->f = fopen(filename, mode); | 320 | p->f = trytoopen(L, filename, mode); |
263 | return (p->f == NULL) ? luaL_fileresult(L, 0, filename) : 1; | 321 | return (p->f == NULL) ? luaL_fileresult(L, 0, filename) : 1; |
264 | } | 322 | } |
265 | 323 | ||
@@ -278,6 +336,8 @@ static int io_popen (lua_State *L) { | |||
278 | const char *mode = luaL_optstring(L, 2, "r"); | 336 | const char *mode = luaL_optstring(L, 2, "r"); |
279 | LStream *p = newprefile(L); | 337 | LStream *p = newprefile(L); |
280 | p->f = l_popen(L, filename, mode); | 338 | p->f = l_popen(L, filename, mode); |
339 | if (p->f == NULL && resourcetryagain(L)) /* resource failure? */ | ||
340 | p->f = l_popen(L, filename, mode); /* try to open again */ | ||
281 | p->closef = &io_pclose; | 341 | p->closef = &io_pclose; |
282 | return (p->f == NULL) ? luaL_fileresult(L, 0, filename) : 1; | 342 | return (p->f == NULL) ? luaL_fileresult(L, 0, filename) : 1; |
283 | } | 343 | } |