Merge branch 'lh/cache'

* lh/cache:
  Add page 'ls_cache'
  Redesign the caching layer

7 files changed, 506 insertions, 216 deletions

diff --git a/cache.c b/cache.c
index 89f7ecd..b701e13 100644
--- a/cache.c
+++ b/cache.c
@@ -4,117 +4,408 @@
  *
  * 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);
+}
+
diff --git a/cache.h b/cache.h
index 4dcbea3..66cc41f 100644
--- a/cache.h
+++ b/cache.h
@@ -6,18 +6,30 @@
 #ifndef CGIT_CACHE_H
 #define CGIT_CACHE_H
 
-struct cacheitem {
-        char *name;
-        struct stat st;
-        int ttl;
-        int fd;
-};
-
-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);
+typedef void (*cache_fill_fn)(void *cbdata);
+
+
+/* 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);
+
+
+/* List info about all cache entries on stdout */
+extern int cache_ls(const char *path);
+
+/* Print a message to stdout */
+extern void cache_log(const char *format, ...);
 
 #endif /* CGIT_CACHE_H */
diff --git a/cgit.c b/cgit.c
index a402758..ccd61f4 100644
--- a/cgit.c
+++ b/cgit.c
@@ -49,6 +49,8 @@ void config_cb(const char *name, const char *value)
                 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"))
@@ -147,6 +149,8 @@ static void prepare_context(struct cgit_context *ctx)
 {
         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;
@@ -168,47 +172,8 @@ static void prepare_context(struct cgit_context *ctx)
         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 {
@@ -293,8 +258,9 @@ static int prepare_repo_cmd(struct cgit_context *ctx)
         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);
@@ -333,82 +299,6 @@ static void process_request(struct cgit_context *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;
@@ -443,13 +333,29 @@ 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;
         cgit_repolist.count = 0;
         cgit_repolist.repos = NULL;
@@ -463,13 +369,15 @@ int main(int argc, const char **argv)
                 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;
 }
diff --git a/cgit.h b/cgit.h
index daebeff..bbb404e 100644
--- a/cgit.h
+++ b/cgit.h
@@ -136,6 +136,7 @@ struct cgit_config {
         char *root_readme;
         char *script_name;
         char *virtual_root;
+        int cache_size;
         int cache_dynamic_ttl;
         int cache_max_create_time;
         int cache_repo_ttl;
diff --git a/cmd.c b/cmd.c
index 6cc91e6..4edca6b 100644
--- a/cmd.c
+++ b/cmd.c
@@ -8,6 +8,8 @@
 
 #include "cgit.h"
 #include "cmd.h"
+#include "cache.h"
+#include "ui-shared.h"
 #include "ui-blob.h"
 #include "ui-commit.h"
 #include "ui-diff.h"
@@ -43,17 +45,25 @@ static void diff_fn(struct cgit_context *ctx)
         cgit_print_diff(ctx->qry.sha1, ctx->qry.sha2, ctx->qry.path);
 }
 
-static void repolist_fn(struct cgit_context *ctx)
-{
-        cgit_print_repolist();
-}
-
 static void log_fn(struct cgit_context *ctx)
 {
         cgit_print_log(ctx->qry.sha1, ctx->qry.ofs, ctx->cfg.max_commit_count,
                        ctx->qry.grep, ctx->qry.search, ctx->qry.path, 1);
 }
 
+static void ls_cache_fn(struct cgit_context *ctx)
+{
+        ctx->page.mimetype = "text/plain";
+        ctx->page.filename = "ls-cache.txt";
+        cgit_print_http_headers(ctx);
+        cache_ls(ctx->cfg.cache_root);
+}
+
+static void repolist_fn(struct cgit_context *ctx)
+{
+        cgit_print_repolist();
+}
+
 static void patch_fn(struct cgit_context *ctx)
 {
         cgit_print_patch(ctx->qry.sha1);
@@ -97,6 +107,7 @@ struct cgit_cmd *cgit_get_cmd(struct cgit_context *ctx)
                 def_cmd(commit, 1, 1),
                 def_cmd(diff, 1, 1),
                 def_cmd(log, 1, 1),
+                def_cmd(ls_cache, 0, 0),
                 def_cmd(patch, 1, 0),
                 def_cmd(refs, 1, 1),
                 def_cmd(repolist, 0, 0),
diff --git a/tests/setup.sh b/tests/setup.sh
index 66bf406..e37306e 100755
--- a/tests/setup.sh
+++ b/tests/setup.sh
@@ -44,7 +44,7 @@ setup_repos()
 virtual-root=/
 cache-root=$PWD/trash/cache
 
-nocache=0
+cache-size=1021
 snapshots=tar.gz tar.bz zip
 enable-log-filecount=1
 enable-log-linecount=1
diff --git a/tests/t0020-validate-cache.sh b/tests/t0020-validate-cache.sh
new file mode 100755
index 0000000..53ec2eb
--- /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