*
* Licensed under GNU General Public License v2
* (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.
+ *
*/
#include "cgit.h"
#include "cache.h"
-const int NOLOCK = -1;
+#define CACHE_BUFSIZE (1024 * 4)
-char *cache_safe_filename(const char *unsafe)
+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];
+};
+
+/* 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;
+
+ while((i=read(slot->cache_fd, slot->buf, sizeof(slot->buf))) > 0)
+ j = write(STDOUT_FILENO, slot->buf, i);
- path = fmt("%s", ctx.cfg.cache_root);
- if (mkdir(path, S_IRWXU) && errno!=EEXIST)
+ 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;
+ }
+
+ /* Verify input, calculate filenames */
+ if (!path) {
+ cache_log("[cgit] Cache path not specified, caching is disabled\n");
+ fn(cbdata);
return 0;
- return item->st.st_mtime + item->ttl * 60 < time(NULL);
+ }
+ 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);
}
+
+/* Return a strftime formatted date/time
+ * NB: the result from this function is to shared memory
+ */
+char *sprintftime(const char *format, time_t time)
+{
+ static char buf[64];
+ struct tm *tm;
+
+ if (!time)
+ return NULL;
+ tm = gmtime(&time);
+ strftime(buf, sizeof(buf)-1, format, tm);
+ return buf;
+}
+
+int cache_ls(const char *path)
+{
+ DIR *dir;
+ struct dirent *ent;
+ int err = 0;
+ struct cache_slot slot;
+ char fullname[1024];
+ char *name;
+
+ if (!path) {
+ cache_log("[cgit] cache path not specified\n");
+ return -1;
+ }
+ if (strlen(path) > 1024 - 10) {
+ cache_log("[cgit] cache path too long: %s\n",
+ path);
+ return -1;
+ }
+ dir = opendir(path);
+ if (!dir) {
+ err = errno;
+ cache_log("[cgit] unable to open path %s: %s (%d)\n",
+ path, strerror(err), err);
+ return err;
+ }
+ strcpy(fullname, path);
+ name = fullname + strlen(path);
+ if (*(name - 1) != '/') {
+ *name++ = '/';
+ *name = '\0';
+ }
+ slot.cache_name = fullname;
+ while((ent = readdir(dir)) != NULL) {
+ if (strlen(ent->d_name) != 8)
+ continue;
+ strcpy(name, ent->d_name);
+ if ((err = open_slot(&slot)) != 0) {
+ cache_log("[cgit] unable to open path %s: %s (%d)\n",
+ fullname, strerror(err), err);
+ continue;
+ }
+ printf("%s %s %10lld %s\n",
+ name,
+ sprintftime("%Y-%m-%d %H:%M:%S",
+ slot.cache_st.st_mtime),
+ slot.cache_st.st_size,
+ slot.buf);
+ close_slot(&slot);
+ }
+ closedir(dir);
+ return 0;
+}
+
+/* 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);
+}
+
ctx.cfg.enable_log_filecount = atoi(value);
else if (!strcmp(name, "enable-log-linecount"))
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"))
ctx.cfg.cache_root = xstrdup(value);
else if (!strcmp(name, "cache-root-ttl"))
{
memset(ctx, 0, sizeof(ctx));
ctx->cfg.agefile = "info/web/last-modified";
+ ctx->cfg.nocache = 0;
+ ctx->cfg.cache_size = 0;
ctx->cfg.cache_dynamic_ttl = 5;
ctx->cfg.cache_max_create_time = 5;
ctx->cfg.cache_repo_ttl = 5;
ctx->page.mimetype = "text/html";
ctx->page.charset = PAGE_ENCODING;
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;
}
struct refmatch {
return 0;
}
-static void process_request(struct cgit_context *ctx)
+static void process_request(void *cbdata)
{
+ struct cgit_context *ctx = cbdata;
struct cgit_cmd *cmd;
cmd = cgit_get_cmd(ctx);
cgit_print_docend();
}
-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)
{
int i;
}
}
+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;
cgit_repolist.count = 0;
cgit_repolist.repos = NULL;
ctx.qry.raw = xstrdup(getenv("QUERY_STRING"));
cgit_parse_args(argc, 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;
}
git.ckatri.com / cgit.git / commitdiff