A hyperfast web frontend for git repositories written in C.
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Lars Hjemli 06fe0c2f47 Add display of tree content w/ui-tree.c
Signed-off-by: Lars Hjemli <hjemli@gmail.com>
2006-12-13 00:13:27 +01:00
.gitignore Add caching infrastructure 2006-12-10 22:31:36 +01:00
cache.c cache_lock: do xstrdup/free on lockfile 2006-12-12 10:16:41 +01:00
cgit.c Add display of tree content w/ui-tree.c 2006-12-13 00:13:27 +01:00
cgit.css Add display of tree content w/ui-tree.c 2006-12-13 00:13:27 +01:00
cgit.h Add display of tree content w/ui-tree.c 2006-12-13 00:13:27 +01:00
COPYING Add license file and copyright notices 2006-12-10 22:41:14 +01:00
git.h Add display of tree content w/ui-tree.c 2006-12-13 00:13:27 +01:00
html.c Add license file and copyright notices 2006-12-10 22:41:14 +01:00
Makefile Add display of tree content w/ui-tree.c 2006-12-13 00:13:27 +01:00
parsing.c Rename config.c to parsing.c + move cgit_parse_query from cgit.c to parsing.c 2006-12-11 16:11:40 +01:00
README Add caching infrastructure 2006-12-10 22:31:36 +01:00
shared.c Move global variables + callback functions into shared.c 2006-12-11 17:25:51 +01:00
ui-log.c Add display of tree content w/ui-tree.c 2006-12-13 00:13:27 +01:00
ui-repolist.c Move functions for repolist output into ui-repolist.c 2006-12-11 16:49:18 +01:00
ui-shared.c Move functions for repolist output into ui-repolist.c 2006-12-11 16:49:18 +01:00
ui-summary.c Add display of tree content w/ui-tree.c 2006-12-13 00:13:27 +01:00
ui-tree.c Add display of tree content w/ui-tree.c 2006-12-13 00:13:27 +01:00
ui-view.c Add display of tree content w/ui-tree.c 2006-12-13 00:13:27 +01:00

Cache algorithm
===============

Cgit normally returns cached pages when invoked. If there is no cache file, or
the cache file has expired, it is regenerated. Finally, the cache file is 
printed on stdout.

When it is decided that a cache file needs to be regenerated, an attempt is 
made to create a corresponding lockfile. If this fails, the process gives up
and uses the expired cache file instead.

When there is no cache file for a request, an attempt is made to create a 
corresponding lockfile. If this fails, the process calls sched_yield(2) before
restarting the request handling.

In pseudocode:

	name = generate_cache_name(request);
top:
	if (!exists(name)) {
		if (lock_cache(name)) {
			generate_cache(request, name);
			unlock_cache(name);
		} else {
			sched_yield();
			goto top;
		}
	} else if (expired(name)) {
		if (lock_cache(name)) {
			generate_cache(request, name);
			unlock_cache(name);
		}
	}
	print_file(name);


The following options can be set in /etc/cgitrc to control cache behaviour:
  cache-root:        root directory for cache files
  cache-root-ttl:    TTL for the repo listing page
  cache-repo-ttl:    TTL for any repos summary page
  cache-dynamic-ttl: TTL for pages with symbolic references (not SHA1)
  cache-static-ttl:  TTL for pages with sha1 references

TTL is specified in minutes, -1 meaning "infinite caching". 


Naming of cache files
---------------------
Repository listing:  <cachedir>/index.html
Repository summary:  <cachedir>/<repo>/index.html
Repository subpage:  <cachedir>/<repo>/<page>/<querystring>.html

The corresponding lock files have a ".lock" suffix.