cgit/cgit.c
Lars Hjemli 939d32fda7 Redesign the caching layer
The original caching layer in cgit has no upper bound on the number of
concurrent cache entries, so when cgit is traversed by a spider (like the
googlebot), the cache might end up filling your disk. Also, if any error
occurs in the cache layer, no content is returned to the client.

This patch redesigns the caching layer to avoid these flaws by
* giving the cache a bound number of slots
* disabling the cache for the current request when errors occur

The cache size limit is implemented by hashing the querystring (the cache
lookup key) and generating a cache filename based on this hash modulo the
cache size. In order to detect hash collisions, the full lookup key (i.e.
the querystring) is stored in the cache file (separated from its associated
content by ascii 0).

The cache filename is the reversed 8-digit hexadecimal representation of

  hash(key) % cache_size

which should make the filesystem lookup pretty fast (if directory content
is indexed/sorted); reversing the representation avoids the problem where
all keys have equal prefix.

There is a new config option, cache-size, which sets the upper bound for
the cache. Default value for this option is 0, which has the same effect
as setting nocache=1 (hence nocache is now deprecated).

Included in this patch is also a new testfile which verifies that the
new option works as intended.

Signed-off-by: Lars Hjemli <hjemli@gmail.com>
2008-04-28 11:32:42 +02:00

370 lines
10 KiB
C

/* cgit.c: cgi for the git scm
*
* Copyright (C) 2006 Lars Hjemli
*
* Licensed under GNU General Public License v2
* (see COPYING for full license text)
*/
#include "cgit.h"
#include "cache.h"
#include "cmd.h"
#include "configfile.h"
#include "html.h"
#include "ui-shared.h"
const char *cgit_version = CGIT_VERSION;
void config_cb(const char *name, const char *value)
{
if (!strcmp(name, "root-title"))
ctx.cfg.root_title = xstrdup(value);
else if (!strcmp(name, "css"))
ctx.cfg.css = xstrdup(value);
else if (!strcmp(name, "logo"))
ctx.cfg.logo = xstrdup(value);
else if (!strcmp(name, "index-header"))
ctx.cfg.index_header = xstrdup(value);
else if (!strcmp(name, "index-info"))
ctx.cfg.index_info = xstrdup(value);
else if (!strcmp(name, "logo-link"))
ctx.cfg.logo_link = xstrdup(value);
else if (!strcmp(name, "module-link"))
ctx.cfg.module_link = xstrdup(value);
else if (!strcmp(name, "virtual-root")) {
ctx.cfg.virtual_root = trim_end(value, '/');
if (!ctx.cfg.virtual_root && (!strcmp(value, "/")))
ctx.cfg.virtual_root = "";
} else if (!strcmp(name, "nocache"))
ctx.cfg.nocache = atoi(value);
else if (!strcmp(name, "snapshots"))
ctx.cfg.snapshots = cgit_parse_snapshots_mask(value);
else if (!strcmp(name, "enable-index-links"))
ctx.cfg.enable_index_links = atoi(value);
else if (!strcmp(name, "enable-log-filecount"))
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"))
ctx.cfg.cache_root_ttl = atoi(value);
else if (!strcmp(name, "cache-repo-ttl"))
ctx.cfg.cache_repo_ttl = atoi(value);
else if (!strcmp(name, "cache-static-ttl"))
ctx.cfg.cache_static_ttl = atoi(value);
else if (!strcmp(name, "cache-dynamic-ttl"))
ctx.cfg.cache_dynamic_ttl = atoi(value);
else if (!strcmp(name, "max-message-length"))
ctx.cfg.max_msg_len = atoi(value);
else if (!strcmp(name, "max-repodesc-length"))
ctx.cfg.max_repodesc_len = atoi(value);
else if (!strcmp(name, "max-commit-count"))
ctx.cfg.max_commit_count = atoi(value);
else if (!strcmp(name, "summary-log"))
ctx.cfg.summary_log = atoi(value);
else if (!strcmp(name, "summary-branches"))
ctx.cfg.summary_branches = atoi(value);
else if (!strcmp(name, "summary-tags"))
ctx.cfg.summary_tags = atoi(value);
else if (!strcmp(name, "agefile"))
ctx.cfg.agefile = xstrdup(value);
else if (!strcmp(name, "renamelimit"))
ctx.cfg.renamelimit = atoi(value);
else if (!strcmp(name, "robots"))
ctx.cfg.robots = xstrdup(value);
else if (!strcmp(name, "clone-prefix"))
ctx.cfg.clone_prefix = xstrdup(value);
else if (!strcmp(name, "repo.group"))
ctx.cfg.repo_group = xstrdup(value);
else if (!strcmp(name, "repo.url"))
ctx.repo = cgit_add_repo(value);
else if (!strcmp(name, "repo.name"))
ctx.repo->name = xstrdup(value);
else if (ctx.repo && !strcmp(name, "repo.path"))
ctx.repo->path = trim_end(value, '/');
else if (ctx.repo && !strcmp(name, "repo.clone-url"))
ctx.repo->clone_url = xstrdup(value);
else if (ctx.repo && !strcmp(name, "repo.desc"))
ctx.repo->desc = xstrdup(value);
else if (ctx.repo && !strcmp(name, "repo.owner"))
ctx.repo->owner = xstrdup(value);
else if (ctx.repo && !strcmp(name, "repo.defbranch"))
ctx.repo->defbranch = xstrdup(value);
else if (ctx.repo && !strcmp(name, "repo.snapshots"))
ctx.repo->snapshots = ctx.cfg.snapshots & cgit_parse_snapshots_mask(value); /* XXX: &? */
else if (ctx.repo && !strcmp(name, "repo.enable-log-filecount"))
ctx.repo->enable_log_filecount = ctx.cfg.enable_log_filecount * atoi(value);
else if (ctx.repo && !strcmp(name, "repo.enable-log-linecount"))
ctx.repo->enable_log_linecount = ctx.cfg.enable_log_linecount * atoi(value);
else if (ctx.repo && !strcmp(name, "repo.module-link"))
ctx.repo->module_link= xstrdup(value);
else if (ctx.repo && !strcmp(name, "repo.readme") && value != NULL) {
if (*value == '/')
ctx.repo->readme = xstrdup(value);
else
ctx.repo->readme = xstrdup(fmt("%s/%s", ctx.repo->path, value));
} else if (!strcmp(name, "include"))
parse_configfile(value, config_cb);
}
static void querystring_cb(const char *name, const char *value)
{
if (!strcmp(name,"r")) {
ctx.qry.repo = xstrdup(value);
ctx.repo = cgit_get_repoinfo(value);
} else if (!strcmp(name, "p")) {
ctx.qry.page = xstrdup(value);
} else if (!strcmp(name, "url")) {
cgit_parse_url(value);
} else if (!strcmp(name, "qt")) {
ctx.qry.grep = xstrdup(value);
} else if (!strcmp(name, "q")) {
ctx.qry.search = xstrdup(value);
} else if (!strcmp(name, "h")) {
ctx.qry.head = xstrdup(value);
ctx.qry.has_symref = 1;
} else if (!strcmp(name, "id")) {
ctx.qry.sha1 = xstrdup(value);
ctx.qry.has_sha1 = 1;
} else if (!strcmp(name, "id2")) {
ctx.qry.sha2 = xstrdup(value);
ctx.qry.has_sha1 = 1;
} else if (!strcmp(name, "ofs")) {
ctx.qry.ofs = atoi(value);
} else if (!strcmp(name, "path")) {
ctx.qry.path = trim_end(value, '/');
} else if (!strcmp(name, "name")) {
ctx.qry.name = xstrdup(value);
}
}
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;
ctx->cfg.cache_root = CGIT_CACHE_ROOT;
ctx->cfg.cache_root_ttl = 5;
ctx->cfg.cache_static_ttl = -1;
ctx->cfg.css = "/cgit.css";
ctx->cfg.logo = "/git-logo.png";
ctx->cfg.max_commit_count = 50;
ctx->cfg.max_lock_attempts = 5;
ctx->cfg.max_msg_len = 60;
ctx->cfg.max_repodesc_len = 60;
ctx->cfg.module_link = "./?repo=%s&page=commit&id=%s";
ctx->cfg.renamelimit = -1;
ctx->cfg.robots = "index, nofollow";
ctx->cfg.root_title = "Git repository browser";
ctx->cfg.script_name = CGIT_SCRIPT_NAME;
ctx->page.mimetype = "text/html";
ctx->page.charset = PAGE_ENCODING;
ctx->page.filename = NULL;
ctx->page.modified = time(NULL);
ctx->page.expires = ctx->page.modified;
}
struct refmatch {
char *req_ref;
char *first_ref;
int match;
};
int find_current_ref(const char *refname, const unsigned char *sha1,
int flags, void *cb_data)
{
struct refmatch *info;
info = (struct refmatch *)cb_data;
if (!strcmp(refname, info->req_ref))
info->match = 1;
if (!info->first_ref)
info->first_ref = xstrdup(refname);
return info->match;
}
char *find_default_branch(struct cgit_repo *repo)
{
struct refmatch info;
info.req_ref = repo->defbranch;
info.first_ref = NULL;
info.match = 0;
for_each_branch_ref(find_current_ref, &info);
if (info.match)
return info.req_ref;
else
return info.first_ref;
}
static int prepare_repo_cmd(struct cgit_context *ctx)
{
char *tmp;
unsigned char sha1[20];
int nongit = 0;
setenv("GIT_DIR", ctx->repo->path, 1);
setup_git_directory_gently(&nongit);
if (nongit) {
ctx->page.title = fmt("%s - %s", ctx->cfg.root_title,
"config error");
tmp = fmt("Not a git repository: '%s'", ctx->repo->path);
ctx->repo = NULL;
cgit_print_http_headers(ctx);
cgit_print_docstart(ctx);
cgit_print_pageheader(ctx);
cgit_print_error(tmp);
cgit_print_docend();
return 1;
}
ctx->page.title = fmt("%s - %s", ctx->repo->name, ctx->repo->desc);
if (!ctx->qry.head) {
ctx->qry.head = xstrdup(find_default_branch(ctx->repo));
ctx->repo->defbranch = ctx->qry.head;
}
if (!ctx->qry.head) {
cgit_print_http_headers(ctx);
cgit_print_docstart(ctx);
cgit_print_pageheader(ctx);
cgit_print_error("Repository seems to be empty");
cgit_print_docend();
return 1;
}
if (get_sha1(ctx->qry.head, sha1)) {
tmp = xstrdup(ctx->qry.head);
ctx->qry.head = ctx->repo->defbranch;
cgit_print_http_headers(ctx);
cgit_print_docstart(ctx);
cgit_print_pageheader(ctx);
cgit_print_error(fmt("Invalid branch: %s", tmp));
cgit_print_docend();
return 1;
}
return 0;
}
static void process_request(void *cbdata)
{
struct cgit_context *ctx = cbdata;
struct cgit_cmd *cmd;
cmd = cgit_get_cmd(ctx);
if (!cmd) {
ctx->page.title = "cgit error";
ctx->repo = NULL;
cgit_print_http_headers(ctx);
cgit_print_docstart(ctx);
cgit_print_pageheader(ctx);
cgit_print_error("Invalid request");
cgit_print_docend();
return;
}
if (cmd->want_repo && prepare_repo_cmd(ctx))
return;
if (cmd->want_layout) {
cgit_print_http_headers(ctx);
cgit_print_docstart(ctx);
cgit_print_pageheader(ctx);
}
cmd->fn(ctx);
if (cmd->want_layout)
cgit_print_docend();
}
static void cgit_parse_args(int argc, const char **argv)
{
int i;
for (i = 1; i < argc; i++) {
if (!strncmp(argv[i], "--cache=", 8)) {
ctx.cfg.cache_root = xstrdup(argv[i]+8);
}
if (!strcmp(argv[i], "--nocache")) {
ctx.cfg.nocache = 1;
}
if (!strncmp(argv[i], "--query=", 8)) {
ctx.qry.raw = xstrdup(argv[i]+8);
}
if (!strncmp(argv[i], "--repo=", 7)) {
ctx.qry.repo = xstrdup(argv[i]+7);
}
if (!strncmp(argv[i], "--page=", 7)) {
ctx.qry.page = xstrdup(argv[i]+7);
}
if (!strncmp(argv[i], "--head=", 7)) {
ctx.qry.head = xstrdup(argv[i]+7);
ctx.qry.has_symref = 1;
}
if (!strncmp(argv[i], "--sha1=", 7)) {
ctx.qry.sha1 = xstrdup(argv[i]+7);
ctx.qry.has_sha1 = 1;
}
if (!strncmp(argv[i], "--ofs=", 6)) {
ctx.qry.ofs = atoi(argv[i]+6);
}
}
}
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)
{
const char *cgit_config_env = getenv("CGIT_CONFIG");
int err, ttl;
prepare_context(&ctx);
cgit_repolist.length = 0;
cgit_repolist.count = 0;
cgit_repolist.repos = NULL;
parse_configfile(cgit_config_env ? cgit_config_env : CGIT_CONFIG,
config_cb);
ctx.repo = NULL;
if (getenv("SCRIPT_NAME"))
ctx.cfg.script_name = xstrdup(getenv("SCRIPT_NAME"));
if (getenv("QUERY_STRING"))
ctx.qry.raw = xstrdup(getenv("QUERY_STRING"));
cgit_parse_args(argc, argv);
http_parse_querystring(ctx.qry.raw, querystring_cb);
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;
}