| -rw-r--r-- | cache.c | 359 | ||||
| -rw-r--r-- | cache.h | 33 | ||||
| -rw-r--r-- | cgit.c | 166 | ||||
| -rw-r--r-- | cgit.h | 1 | ||||
| -rwxr-xr-x | tests/setup.sh | 2 | ||||
| -rwxr-xr-x | tests/t0020-validate-cache.sh | 67 |
6 files changed, 418 insertions, 210 deletions
@@ -6,2 +6,9 @@ * (see COPYING for full license text) + * + * + * The cache is just a directory structure where each file is a cache slot, + * and each filename is based on the hash of some key (e.g. the cgit url). + * Each file contains the full key followed by the cached content for that + * key. + * */ @@ -11,110 +18,326 @@ -const int NOLOCK = -1; +#define CACHE_BUFSIZE (1024 * 4) + +struct cache_slot { + const char *key; + int keylen; + int ttl; + cache_fill_fn fn; + void *cbdata; + int cache_fd; + int lock_fd; + const char *cache_name; + const char *lock_name; + int match; + struct stat cache_st; + struct stat lock_st; + int bufsize; + char buf[CACHE_BUFSIZE]; +}; -char *cache_safe_filename(const char *unsafe) +/* Open an existing cache slot and fill the cache buffer with + * (part of) the content of the cache file. Return 0 on success + * and errno otherwise. + */ +static int open_slot(struct cache_slot *slot) { - static char buf[4][PATH_MAX]; - static int bufidx; - char *s; - char c; - - bufidx++; - bufidx &= 3; - s = buf[bufidx]; - - while(unsafe && (c = *unsafe++) != 0) { - if (c == '/' || c == ' ' || c == '&' || c == '|' || - c == '>' || c == '<' || c == '.') - c = '_'; - *s++ = c; - } - *s = '\0'; - return buf[bufidx]; + char *bufz; + int bufkeylen = -1; + + slot->cache_fd = open(slot->cache_name, O_RDONLY); + if (slot->cache_fd == -1) + return errno; + + if (fstat(slot->cache_fd, &slot->cache_st)) + return errno; + + slot->bufsize = read(slot->cache_fd, slot->buf, sizeof(slot->buf)); + if (slot->bufsize == 0) + return errno; + + bufz = memchr(slot->buf, 0, slot->bufsize); + if (bufz) + bufkeylen = bufz - slot->buf; + + slot->match = bufkeylen == slot->keylen && + !memcmp(slot->key, slot->buf, bufkeylen + 1); + + return 0; } -int cache_exist(struct cacheitem *item) +/* Close the active cache slot */ +static void close_slot(struct cache_slot *slot) { - if (stat(item->name, &item->st)) { - item->st.st_mtime = 0; - return 0; + if (slot->cache_fd > 0) { + close(slot->cache_fd); + slot->cache_fd = -1; } - return 1; } -int cache_create_dirs() +/* Print the content of the active cache slot (but skip the key). */ +static int print_slot(struct cache_slot *slot) { - char *path; + ssize_t i, j = 0; + + i = lseek(slot->cache_fd, slot->keylen + 1, SEEK_SET); + if (i != slot->keylen + 1) + return errno; - path = fmt("%s", ctx.cfg.cache_root); - if (mkdir(path, S_IRWXU) && errno!=EEXIST) + while((i=read(slot->cache_fd, slot->buf, sizeof(slot->buf))) > 0) + j = write(STDOUT_FILENO, slot->buf, i); + + if (j < 0) + return errno; + else return 0; +} - if (!ctx.repo) +/* Check if the slot has expired */ +static int is_expired(struct cache_slot *slot) +{ + if (slot->ttl < 0) return 0; + else + return slot->cache_st.st_mtime + slot->ttl*60 < time(NULL); +} - path = fmt("%s/%s", ctx.cfg.cache_root, - cache_safe_filename(ctx.repo->url)); +/* Check if the slot has been modified since we opened it. + * NB: If stat() fails, we pretend the file is modified. + */ +static int is_modified(struct cache_slot *slot) +{ + struct stat st; - if (mkdir(path, S_IRWXU) && errno!=EEXIST) - return 0; + if (stat(slot->cache_name, &st)) + return 1; + return (st.st_ino != slot->cache_st.st_ino || + st.st_mtime != slot->cache_st.st_mtime || + st.st_size != slot->cache_st.st_size); +} - if (ctx.qry.page) { - path = fmt("%s/%s/%s", ctx.cfg.cache_root, - cache_safe_filename(ctx.repo->url), - ctx.qry.page); - if (mkdir(path, S_IRWXU) && errno!=EEXIST) - return 0; +/* Close an open lockfile */ +static void close_lock(struct cache_slot *slot) +{ + if (slot->lock_fd > 0) { + close(slot->lock_fd); + slot->lock_fd = -1; } - return 1; } -int cache_refill_overdue(const char *lockfile) +/* Create a lockfile used to store the generated content for a cache + * slot, and write the slot key + \0 into it. + * Returns 0 on success and errno otherwise. + */ +static int lock_slot(struct cache_slot *slot) { - struct stat st; + slot->lock_fd = open(slot->lock_name, O_RDWR|O_CREAT|O_EXCL, + S_IRUSR|S_IWUSR); + if (slot->lock_fd == -1) + return errno; + write(slot->lock_fd, slot->key, slot->keylen + 1); + return 0; +} - if (stat(lockfile, &st)) - return 0; +/* Release the current lockfile. If `replace_old_slot` is set the + * lockfile replaces the old cache slot, otherwise the lockfile is + * just deleted. + */ +static int unlock_slot(struct cache_slot *slot, int replace_old_slot) +{ + int err; + + if (replace_old_slot) + err = rename(slot->lock_name, slot->cache_name); else - return (time(NULL) - st.st_mtime > ctx.cfg.cache_max_create_time); + err = unlink(slot->lock_name); + return err; } -int cache_lock(struct cacheitem *item) +/* Generate the content for the current cache slot by redirecting + * stdout to the lock-fd and invoking the callback function + */ +static int fill_slot(struct cache_slot *slot) { - int i = 0; - char *lockfile = xstrdup(fmt("%s.lock", item->name)); + int tmp; - top: - if (++i > ctx.cfg.max_lock_attempts) - die("cache_lock: unable to lock %s: %s", - item->name, strerror(errno)); + /* Preserve stdout */ + tmp = dup(STDOUT_FILENO); + if (tmp == -1) + return errno; - item->fd = open(lockfile, O_WRONLY|O_CREAT|O_EXCL, S_IRUSR|S_IWUSR); + /* Redirect stdout to lockfile */ + if (dup2(slot->lock_fd, STDOUT_FILENO) == -1) + return errno; - if (item->fd == NOLOCK && errno == ENOENT && cache_create_dirs()) - goto top; + /* Generate cache content */ + slot->fn(slot->cbdata); - if (item->fd == NOLOCK && errno == EEXIST && - cache_refill_overdue(lockfile) && !unlink(lockfile)) - goto top; + /* Restore stdout */ + if (dup2(tmp, STDOUT_FILENO) == -1) + return errno; - free(lockfile); - return (item->fd > 0); + /* Close the temporary filedescriptor */ + close(tmp); + return 0; } -int cache_unlock(struct cacheitem *item) +/* Crude implementation of 32-bit FNV-1 hash algorithm, + * see http://www.isthe.com/chongo/tech/comp/fnv/ for details + * about the magic numbers. + */ +#define FNV_OFFSET 0x811c9dc5 +#define FNV_PRIME 0x01000193 + +unsigned long hash_str(const char *str) { - close(item->fd); - return (rename(fmt("%s.lock", item->name), item->name) == 0); + unsigned long h = FNV_OFFSET; + unsigned char *s = (unsigned char *)str; + + if (!s) + return h; + + while(*s) { + h *= FNV_PRIME; + h ^= *s++; + } + return h; } -int cache_cancel_lock(struct cacheitem *item) +static int process_slot(struct cache_slot *slot) { - return (unlink(fmt("%s.lock", item->name)) == 0); + int err; + + err = open_slot(slot); + if (!err && slot->match) { + if (is_expired(slot)) { + if (!lock_slot(slot)) { + /* If the cachefile has been replaced between + * `open_slot` and `lock_slot`, we'll just + * serve the stale content from the original + * cachefile. This way we avoid pruning the + * newly generated slot. The same code-path + * is chosen if fill_slot() fails for some + * reason. + * + * TODO? check if the new slot contains the + * same key as the old one, since we would + * prefer to serve the newest content. + * This will require us to open yet another + * file-descriptor and read and compare the + * key from the new file, so for now we're + * lazy and just ignore the new file. + */ + if (is_modified(slot) || fill_slot(slot)) { + unlock_slot(slot, 0); + close_lock(slot); + } else { + close_slot(slot); + unlock_slot(slot, 1); + slot->cache_fd = slot->lock_fd; + } + } + } + print_slot(slot); + close_slot(slot); + return 0; + } + + /* If the cache slot does not exist (or its key doesn't match the + * current key), lets try to create a new cache slot for this + * request. If this fails (for whatever reason), lets just generate + * the content without caching it and fool the caller to belive + * everything worked out (but print a warning on stdout). + */ + + close_slot(slot); + if ((err = lock_slot(slot)) != 0) { + cache_log("[cgit] Unable to lock slot %s: %s (%d)\n", + slot->lock_name, strerror(err), err); + slot->fn(slot->cbdata); + return 0; + } + + if ((err = fill_slot(slot)) != 0) { + cache_log("[cgit] Unable to fill slot %s: %s (%d)\n", + slot->lock_name, strerror(err), err); + unlock_slot(slot, 0); + close_lock(slot); + slot->fn(slot->cbdata); + return 0; + } + // We've got a valid cache slot in the lock file, which + // is about to replace the old cache slot. But if we + // release the lockfile and then try to open the new cache + // slot, we might get a race condition with a concurrent + // writer for the same cache slot (with a different key). + // Lets avoid such a race by just printing the content of + // the lock file. + slot->cache_fd = slot->lock_fd; + unlock_slot(slot, 1); + err = print_slot(slot); + close_slot(slot); + return err; } -int cache_expired(struct cacheitem *item) +/* Print cached content to stdout, generate the content if necessary. */ +int cache_process(int size, const char *path, const char *key, int ttl, + cache_fill_fn fn, void *cbdata) { - if (item->ttl < 0) + unsigned long hash; + int len, i; + char filename[1024]; + char lockname[1024 + 5]; /* 5 = ".lock" */ + struct cache_slot slot; + + /* If the cache is disabled, just generate the content */ + if (size <= 0) { + fn(cbdata); return 0; - return item->st.st_mtime + item->ttl * 60 < time(NULL); + } + + /* Verify input, calculate filenames */ + if (!path) { + cache_log("[cgit] Cache path not specified, caching is disabled\n"); + fn(cbdata); + return 0; + } + len = strlen(path); + if (len > sizeof(filename) - 10) { /* 10 = "/01234567\0" */ + cache_log("[cgit] Cache path too long, caching is disabled: %s\n", + path); + fn(cbdata); + return 0; + } + if (!key) + key = ""; + hash = hash_str(key) % size; + strcpy(filename, path); + if (filename[len - 1] != '/') + filename[len++] = '/'; + for(i = 0; i < 8; i++) { + sprintf(filename + len++, "%x", + (unsigned char)(hash & 0xf)); + hash >>= 4; + } + filename[len] = '\0'; + strcpy(lockname, filename); + strcpy(lockname + len, ".lock"); + slot.fn = fn; + slot.cbdata = cbdata; + slot.ttl = ttl; + slot.cache_name = filename; + slot.lock_name = lockname; + slot.key = key; + slot.keylen = strlen(key); + return process_slot(&slot); } + +/* Print a message to stdout */ +void cache_log(const char *format, ...) +{ + va_list args; + va_start(args, format); + vfprintf(stderr, format, args); + va_end(args); +} + @@ -8,15 +8,24 @@ -struct cacheitem { - char *name; - struct stat st; - int ttl; - int fd; -}; +typedef void (*cache_fill_fn)(void *cbdata); -extern char *cache_safe_filename(const char *unsafe); -extern int cache_lock(struct cacheitem *item); -extern int cache_unlock(struct cacheitem *item); -extern int cache_cancel_lock(struct cacheitem *item); -extern int cache_exist(struct cacheitem *item); -extern int cache_expired(struct cacheitem *item); + +/* Print cached content to stdout, generate the content if necessary. + * + * Parameters + * size max number of cache files + * path directory used to store cache files + * key the key used to lookup cache files + * ttl max cache time in seconds for this key + * fn content generator function for this key + * cbdata user-supplied data to the content generator function + * + * Return value + * 0 indicates success, everyting else is an error + */ +extern int cache_process(int size, const char *path, const char *key, int ttl, + cache_fill_fn fn, void *cbdata); + + +/* Print a message to stdout */ +extern void cache_log(const char *format, ...); @@ -47,2 +47,4 @@ void config_cb(const char *name, const char *value) ctx.cfg.enable_log_linecount = atoi(value); + else if (!strcmp(name, "cache-size")) + ctx.cfg.cache_size = atoi(value); else if (!strcmp(name, "cache-root")) @@ -145,2 +147,4 @@ static void prepare_context(struct cgit_context *ctx) ctx->cfg.agefile = "info/web/last-modified"; + ctx->cfg.nocache = 0; + ctx->cfg.cache_size = 0; ctx->cfg.cache_dynamic_ttl = 5; @@ -165,43 +169,4 @@ static void prepare_context(struct cgit_context *ctx) ctx->page.filename = NULL; -} - -static int cgit_prepare_cache(struct cacheitem *item) -{ - if (!ctx.repo && ctx.qry.repo) { - ctx.page.title = fmt("%s - %s", ctx.cfg.root_title, - "Bad request"); - cgit_print_http_headers(&ctx); - cgit_print_docstart(&ctx); - cgit_print_pageheader(&ctx); - cgit_print_error(fmt("Unknown repo: %s", ctx.qry.repo)); - cgit_print_docend(); - return 0; - } - - if (!ctx.repo) { - item->name = xstrdup(fmt("%s/index.%s.html", - ctx.cfg.cache_root, - cache_safe_filename(ctx.qry.raw))); - item->ttl = ctx.cfg.cache_root_ttl; - return 1; - } - - if (!ctx.qry.page) { - item->name = xstrdup(fmt("%s/%s/index.%s.html", ctx.cfg.cache_root, - cache_safe_filename(ctx.repo->url), - cache_safe_filename(ctx.qry.raw))); - item->ttl = ctx.cfg.cache_repo_ttl; - } else { - item->name = xstrdup(fmt("%s/%s/%s/%s.html", ctx.cfg.cache_root, - cache_safe_filename(ctx.repo->url), - ctx.qry.page, - cache_safe_filename(ctx.qry.raw))); - if (ctx.qry.has_symref) - item->ttl = ctx.cfg.cache_dynamic_ttl; - else if (ctx.qry.has_sha1) - item->ttl = ctx.cfg.cache_static_ttl; - else - item->ttl = ctx.cfg.cache_repo_ttl; - } - return 1; + ctx->page.modified = time(NULL); + ctx->page.expires = ctx->page.modified; } @@ -290,4 +255,5 @@ static int prepare_repo_cmd(struct cgit_context *ctx) -static void process_request(struct cgit_context *ctx) +static void process_request(void *cbdata) { + struct cgit_context *ctx = cbdata; struct cgit_cmd *cmd; @@ -321,78 +287,2 @@ static void process_request(struct cgit_context *ctx) -static long ttl_seconds(long ttl) -{ - if (ttl<0) - return 60 * 60 * 24 * 365; - else - return ttl * 60; -} - -static void cgit_fill_cache(struct cacheitem *item, int use_cache) -{ - int stdout2; - - if (use_cache) { - stdout2 = chk_positive(dup(STDOUT_FILENO), - "Preserving STDOUT"); - chk_zero(close(STDOUT_FILENO), "Closing STDOUT"); - chk_positive(dup2(item->fd, STDOUT_FILENO), "Dup2(cachefile)"); - } - - ctx.page.modified = time(NULL); - ctx.page.expires = ctx.page.modified + ttl_seconds(item->ttl); - process_request(&ctx); - - if (use_cache) { - chk_zero(close(STDOUT_FILENO), "Close redirected STDOUT"); - chk_positive(dup2(stdout2, STDOUT_FILENO), - "Restoring original STDOUT"); - chk_zero(close(stdout2), "Closing temporary STDOUT"); - } -} - -static void cgit_check_cache(struct cacheitem *item) -{ - int i = 0; - - top: - if (++i > ctx.cfg.max_lock_attempts) { - die("cgit_refresh_cache: unable to lock %s: %s", - item->name, strerror(errno)); - } - if (!cache_exist(item)) { - if (!cache_lock(item)) { - sleep(1); - goto top; - } - if (!cache_exist(item)) { - cgit_fill_cache(item, 1); - cache_unlock(item); - } else { - cache_cancel_lock(item); - } - } else if (cache_expired(item) && cache_lock(item)) { - if (cache_expired(item)) { - cgit_fill_cache(item, 1); - cache_unlock(item); - } else { - cache_cancel_lock(item); - } - } -} - -static void cgit_print_cache(struct cacheitem *item) -{ - static char buf[4096]; - ssize_t i; - - int fd = open(item->name, O_RDONLY); - if (fd<0) - die("Unable to open cached file %s", item->name); - - while((i=read(fd, buf, sizeof(buf))) > 0) - write(STDOUT_FILENO, buf, i); - - close(fd); -} - static void cgit_parse_args(int argc, const char **argv) @@ -431,9 +321,25 @@ static void cgit_parse_args(int argc, const char **argv) +static int calc_ttl() +{ + if (!ctx.repo) + return ctx.cfg.cache_root_ttl; + + if (!ctx.qry.page) + return ctx.cfg.cache_repo_ttl; + + if (ctx.qry.has_symref) + return ctx.cfg.cache_dynamic_ttl; + + if (ctx.qry.has_sha1) + return ctx.cfg.cache_static_ttl; + + return ctx.cfg.cache_repo_ttl; +} + int main(int argc, const char **argv) { - struct cacheitem item; const char *cgit_config_env = getenv("CGIT_CONFIG"); + int err, ttl; prepare_context(&ctx); - item.st.st_mtime = time(NULL); cgit_repolist.length = 0; @@ -451,11 +357,13 @@ int main(int argc, const char **argv) http_parse_querystring(ctx.qry.raw, querystring_cb); - if (!cgit_prepare_cache(&item)) - return 0; - if (ctx.cfg.nocache) { - cgit_fill_cache(&item, 0); - } else { - cgit_check_cache(&item); - cgit_print_cache(&item); - } - return 0; + + ttl = calc_ttl(); + ctx.page.expires += ttl*60; + if (ctx.cfg.nocache) + ctx.cfg.cache_size = 0; + err = cache_process(ctx.cfg.cache_size, ctx.cfg.cache_root, + ctx.qry.raw, ttl, process_request, &ctx); + if (err) + cache_log("[cgit] error %d - %s\n", + err, strerror(err)); + return err; } @@ -136,2 +136,3 @@ struct cgit_config { char *virtual_root; + int cache_size; int cache_dynamic_ttl; diff --git a/tests/setup.sh b/tests/setup.sh index 66bf406..e37306e 100755 --- a/tests/setup.sh +++ b/tests/setup.sh @@ -46,3 +46,3 @@ cache-root=$PWD/trash/cache -nocache=0 +cache-size=1021 snapshots=tar.gz tar.bz zip diff --git a/tests/t0020-validate-cache.sh b/tests/t0020-validate-cache.sh new file mode 100755 index 0000000..53ec2eb --- a/dev/null +++ b/tests/t0020-validate-cache.sh @@ -0,0 +1,67 @@ +#!/bin/sh + +. ./setup.sh + +prepare_tests 'Validate cache' + +run_test 'verify cache-size=0' ' + + rm -f trash/cache/* && + sed -i -e "s/cache-size=1021$/cache-size=0/" trash/cgitrc && + cgit_url "" && + cgit_url "foo" && + cgit_url "foo/refs" && + cgit_url "foo/tree" && + cgit_url "foo/log" && + cgit_url "foo/diff" && + cgit_url "foo/patch" && + cgit_url "bar" && + cgit_url "bar/refs" && + cgit_url "bar/tree" && + cgit_url "bar/log" && + cgit_url "bar/diff" && + cgit_url "bar/patch" && + test 0 -eq $(ls trash/cache | wc -l) +' + +run_test 'verify cache-size=1' ' + + rm -f trash/cache/* && + sed -i -e "s/cache-size=0$/cache-size=1/" trash/cgitrc && + cgit_url "" && + cgit_url "foo" && + cgit_url "foo/refs" && + cgit_url "foo/tree" && + cgit_url "foo/log" && + cgit_url "foo/diff" && + cgit_url "foo/patch" && + cgit_url "bar" && + cgit_url "bar/refs" && + cgit_url "bar/tree" && + cgit_url "bar/log" && + cgit_url "bar/diff" && + cgit_url "bar/patch" && + test 1 -eq $(ls trash/cache | wc -l) +' + +run_test 'verify cache-size=1021' ' + + rm -f trash/cache/* && + sed -i -e "s/cache-size=1$/cache-size=1021/" trash/cgitrc && + cgit_url "" && + cgit_url "foo" && + cgit_url "foo/refs" && + cgit_url "foo/tree" && + cgit_url "foo/log" && + cgit_url "foo/diff" && + cgit_url "foo/patch" && + cgit_url "bar" && + cgit_url "bar/refs" && + cgit_url "bar/tree" && + cgit_url "bar/log" && + cgit_url "bar/diff" && + cgit_url "bar/patch" && + test 13 -eq $(ls trash/cache | wc -l) +' + +tests_done |