From 939d32fda70ea66c9db51687beb3cea6da7b0599 Mon Sep 17 00:00:00 2001 From: Lars Hjemli Date: Mon, 28 Apr 2008 11:32:42 +0200 Subject: 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 --- tests/setup.sh | 2 +- tests/t0020-validate-cache.sh | 67 +++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 68 insertions(+), 1 deletion(-) create mode 100755 tests/t0020-validate-cache.sh (limited to 'tests') 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 -- cgit v1.2.3-70-g09d2