mod_cache.c revision 5357892a1e367372dc2d4a315156e3e44dc5d56d
/* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "mod_cache.h"
/* -------------------------------------------------------------- */
/* Handles for cache filters, resolved at startup to eliminate
* a name-to-function mapping on each request
*/
static ap_filter_rec_t *cache_save_filter_handle;
static ap_filter_rec_t *cache_out_filter_handle;
/*
* CACHE handler
* -------------
*
* Can we deliver this request from the cache?
* If yes:
* deliver the content by installing the CACHE_OUT filter.
* If no:
* check whether we're allowed to try cache it
* If yes:
* add CACHE_SAVE filter
* If No:
* oh well.
*/
{
const char *auth;
/* Delay initialization until we know we are handling a GET */
if (r->method_number != M_GET) {
return DECLINED;
}
&cache_module);
/*
* Which cache module (if any) should handle this request?
*/
return DECLINED;
}
/* make space for the per request config */
&cache_module);
if (!cache) {
}
/* save away the possible providers */
/*
* Are we allowed to serve cached info at all?
*/
/* find certain cache controlling headers */
/* First things first - does the request allow us to return
* cached information at all? If not, just decline the request.
*/
if (auth) {
return DECLINED;
}
/*
* Try to serve this request from the cache.
*
* If no existing cache file (DECLINED)
* add cache_save filter
* If cached file (OK)
* clear filter stack
* add cache_out filter
* return OK
*/
rv = cache_select(r);
if (!lookup) {
/* try to obtain a cache lock at this point. if we succeed,
* we are the first to try and cache this url. if we fail,
* it means someone else is already trying to cache this
* url, and we should just let the request through to the
* backend without any attempt to cache. this stops
* duplicated simultaneous attempts to cache an entity.
*/
if (APR_SUCCESS == rv) {
/*
* Add cache_save filter to cache this request. Choose
* the correct filter by checking if we are a subrequest
* or not.
*/
if (r->main) {
r->server,
"Adding CACHE_SAVE_SUBREQ filter for %s",
r->uri);
NULL, r, r->connection);
}
else {
r->server, "Adding CACHE_SAVE filter for %s",
r->uri);
NULL, r, r->connection);
}
"Adding CACHE_REMOVE_URL filter for %s",
r->uri);
/* Add cache_remove_url filter to this request to remove a
* stale cache entry if needed. Also put the current cache
* request rec in the filter context, as the request that
* is available later during running the filter maybe
* different due to an internal redirect.
*/
cache, r, r->connection);
}
else {
r->server, "Cache locked for url, not caching "
"response: %s", r->uri);
}
}
else {
if (cache->stale_headers) {
r->server, "Restoring request headers for %s",
r->uri);
}
/* Delete our per-request configuration. */
}
}
else {
/* error */
"cache: error returned while checking for cached "
}
return DECLINED;
}
/* if we are a lookup, we are exiting soon one way or another; Restore
* the headers. */
if (lookup) {
if (cache->stale_headers) {
"Restoring request headers.");
}
/* Delete our per-request configuration. */
}
rv = ap_meets_conditions(r);
/* If we are a lookup, we have to return DECLINED as we have no
* way of knowing if we will be able to serve the content.
*/
if (lookup) {
return DECLINED;
}
/* Return cached status. */
return rv;
}
/* If we're a lookup, we can exit now instead of serving the content. */
if (lookup) {
return OK;
}
/* Serve up the content */
/* We are in the quick handler hook, which means that no output
* filters have been set. So lets run the insert_filter hook.
*/
/*
* Add cache_out filter to serve this request. Choose
* the correct filter by checking if we are a subrequest
* or not.
*/
if (r->main) {
}
else {
}
/*
* Remove all filters that are before the cache_out filter. This ensures
* that we kick off the filter stack with our cache_out filter being the
* first in the chain. This make sense because we want to restore things
* in the same manner as we saved them.
* There may be filters before our cache_out filter, because
*
* 1. We call ap_set_content_type during cache_select. This causes
* Content-Type specific filters to be added.
* 2. We call the insert_filter hook. This causes filters e.g. like
* the ones set with SetOutputFilter to be added.
*/
next = r->output_filters;
}
/* kick off the filter stack */
if (rv != APR_SUCCESS) {
if (rv != AP_FILTER_ERROR) {
"cache: error returned while trying to return %s "
"cached data",
}
return rv;
}
return OK;
}
/*
* CACHE_OUT filter
* ----------------
*
* Deliver cached content (headers and body) up the stack.
*/
{
request_rec *r = f->r;
&cache_module);
if (!cache) {
/* user likely configured CACHE_OUT manually; they should use mod_cache
* configuration to do that */
"CACHE_OUT enabled unexpectedly");
}
"cache: running CACHE_OUT filter");
/* restore status of cached response */
/* XXX: This exposes a bug in mem_cache, since it does not
* restore the status into it's handle. */
/* recall_headers() was called in cache_select() */
/* This filter is done once it has served up its content */
"cache: serving %s", r->uri);
}
/* Find out the size of the cached response body.
Returns -1 if unable to do so.
*/
{
/* There's not an API to ask the cache provider for the size
directly, so retrieve it and count the bytes.
But it's not as inefficient as it might look. mod_disk_cache
will just create a file bucket and set its length to the file
size, and we'll access that length here without ever having to
read the cached file.
If there's some other cache provider that has to read the whole
cached body to fill in the brigade, though, that would make
this rather expensive.
XXX Add a standard cache provider API to get the size of the
cached data.
*/
if (rv != APR_SUCCESS) {
"cache: error recalling body");
/* try to remove cache entry, it's probably messed up */
}
else {
int all_buckets_here = 0;
apr_bucket *e;
size=0;
for (e = APR_BRIGADE_FIRST(bb);
e != APR_BRIGADE_SENTINEL(bb);
e = APR_BUCKET_NEXT(e)) {
if (APR_BUCKET_IS_EOS(e)) {
break;
}
if (APR_BUCKET_IS_FLUSH(e)) {
continue;
}
break;
}
}
if (!all_buckets_here) {
size = -1;
}
}
return size;
}
/* Check that the response body we cached has the same length
* as the Content-Length header, if available. If not, cancel
* caching this response.
*/
{
"but response body size was %"APR_OFF_T_FMT
", removing url from cache: %s",
r->unparsed_uri
);
/* Probably a mod_disk_cache cache area has been (re)mounted
* read-only, or that there is a permissions problem.
*/
"cache: attempt to remove url from cache unsuccessful.");
}
}
}
return rv;
}
/*
* CACHE_SAVE filter
* ---------------
*
* Decide whether or not this content should be cached.
* If we decide no it should not:
* remove the filter from the chain
* If we decide yes it should:
* Have we already started saving the response?
* If we have started, pass the data to the storage manager via store_body
* Otherwise:
* Check to see if we *can* save this particular response.
* If we can, call cache_create_entity() and save the headers and body
* Finally, pass the data to the next filter (the network or whatever)
*
* After the various failure cases, the cache lock is proactively removed, so
* that another request is given the opportunity to attempt to cache without
* waiting for a potentially slow client to acknowledge the failure.
*/
{
request_rec *r = f->r;
char *reason;
apr_pool_t *p;
apr_bucket *e;
&cache_module);
/* Setup cache_request_rec */
&cache_module);
if (!cache) {
/* user likely configured CACHE_SAVE manually; they should really use
* mod_cache configuration to do that
*/
}
p = r->pool;
/*
* Pass Data to Cache
* ------------------
* This section passes the brigades into the cache modules, but only
* if the setup section (see below) is complete.
*/
if (cache->block_response) {
/* We've already sent down the response and EOS. So, ignore
* whatever comes now.
*/
return APR_SUCCESS;
}
/* have we already run the cachability check and set up the
* cached file handle?
*/
if (cache->in_checked) {
/* pass the brigades into the cache, then pass them
* up the filter stack
*/
if (rv != APR_SUCCESS) {
"cache: Cache provider's store_body failed!");
/* give someone else the chance to cache the file */
}
else {
/* proactively remove the lock as soon as we see the eos bucket */
}
/* Was this the final bucket? If yes, perform sanity checks. */
}
}
/*
* Setup Data in Cache
* -------------------
* This section opens the cache entity and sets various caching
* parameters, and decides whether this URL should be cached at
* all. This section is* run before the above section.
*/
/* read expiry date; if a bad date, then leave it so the client can
* read it
*/
}
}
}
else {
exp = APR_DATE_BAD;
}
/* read the last-modified date; if the date is bad, then delete it */
}
if (lastmod == APR_DATE_BAD) {
}
}
else {
}
/* read the etag and cache-control from the entity */
}
}
/*
* what responses should we not cache?
*
* At this point we decide based on the response headers whether it
* is appropriate _NOT_ to cache the data from the server. There are
* a whole lot of conditions that prevent us from caching this data.
* They are tested here one by one to be clear and unambiguous.
*/
&& r->status != HTTP_MULTIPLE_CHOICES
&& r->status != HTTP_MOVED_PERMANENTLY
&& r->status != HTTP_NOT_MODIFIED) {
/* RFC2616 13.4 we are allowed to cache 200, 203, 206, 300, 301 or 410
* We don't cache 206, because we don't (yet) cache partial responses.
* We include 304 Not Modified here too as this is the origin server
* telling us to serve the cached copy.
*/
/* We are also allowed to cache any response given that it has a
* valid Expires or Cache Control header. If we find a either of
* those here, we pass request through the rest of the tests. From
* the RFC:
*
* A response received with any other status code (e.g. status
* codes 302 and 307) MUST NOT be returned in a reply to a
* subsequent request unless there are cache-control directives or
* another header(s) that explicitly allow it. For example, these
* include the following: an Expires header (section 14.21); a
* "max-age", "s-maxage", "must-revalidate", "proxy-revalidate",
* "public" or "private" cache-control directive (section 14.9).
*/
}
else {
}
}
if (reason) {
/* noop */
}
/* if a broken Expires header is present, don't cache it */
}
{
/* if a Expires header is in the past, don't cache it */
reason = "Expires header already expired, not cacheable";
}
/* if a query string is present but no explicit expiration time,
* don't cache it (RFC 2616/13.9 & 13.2.1)
*/
reason = "Query string present but no explicit expiration time";
}
else if (r->status == HTTP_NOT_MODIFIED &&
/* if the server said 304 Not Modified but we have no cache
* file - pass this untouched to the user agent, it's not for us.
*/
reason = "HTTP Status 304 Not Modified";
}
/* 200 OK response from HTTP/1.0 and up without Last-Modified,
* Etag, or Expires headers.
*/
/* Note: mod-include clears last_modified/expires/etags - this
* is why we have an optional function for a key-gen ;-)
*/
reason = "No Last-Modified, Etag, or Expires headers";
}
/* Forbid HEAD requests unless we have it cached already */
reason = "HTTP HEAD request";
}
else if (!conf->store_nostore &&
/* RFC2616 14.9.2 Cache-Control: no-store response
* indicating do not cache, or stop now if you are
* trying to cache it.
*/
/* FIXME: The Cache-Control: no-store could have come in on a 304,
* FIXME: while the original request wasn't conditional. IOW, we
* FIXME: made the the request conditional earlier to revalidate
* FIXME: our cached response.
*/
reason = "Cache-Control: no-store present";
}
else if (!conf->store_private &&
/* RFC2616 14.9.1 Cache-Control: private response
* this object is marked for this user's eyes only. Behave
* as a tunnel.
*/
/* FIXME: See above (no-store) */
reason = "Cache-Control: private present";
}
/* RFC2616 14.8 Authorisation:
* if authorisation is included in the request, we don't cache,
* but we can cache if the following exceptions are true:
* 1) If Cache-Control: s-maxage is included
* 2) If Cache-Control: must-revalidate is included
* 3) If Cache-Control: public is included
*/
reason = "Authorization required";
}
else if (ap_cache_liststr(NULL,
"*", NULL)) {
reason = "Vary header contains '*'";
}
reason = "environment variable 'no-cache' is set";
}
else if (r->no_cache) {
/* or we've been asked not to cache it above */
reason = "r->no_cache present";
}
if (reason) {
"cache: %s not cached. Reason: %s", r->unparsed_uri,
reason);
/* remove this filter from the chain */
/* remove the lock file unconditionally */
/* ship the data up the stack */
}
/* Make it so that we don't execute this path again. */
/* Set the content length if known.
*/
}
if (cl) {
char *errp;
}
}
if (!cl) {
/* if we don't get the content-length, see if we have all the
* buckets and use their length to calculate the size
*/
int all_buckets_here=0;
int unresolved_length = 0;
size=0;
for (e = APR_BRIGADE_FIRST(in);
e != APR_BRIGADE_SENTINEL(in);
e = APR_BUCKET_NEXT(e))
{
if (APR_BUCKET_IS_EOS(e)) {
break;
}
if (APR_BUCKET_IS_FLUSH(e)) {
unresolved_length = 1;
continue;
}
break;
}
}
if (!all_buckets_here) {
size = -1;
}
}
/* remember content length to check response size against later */
/* It's safe to cache the response.
*
* There are two possiblities at this point:
* - cache->handle == NULL. In this case there is no previously
* cached entity anywhere on the system. We must create a brand
* new entity and store the response in it.
* - cache->stale_handle != NULL. In this case there is a stale
* entity in the system which needs to be replaced by new
* content (unless the result was 304 Not Modified, which means
* the cached entity is actually fresh, and we should update
* the headers).
*/
/* Did we have a stale cache entry that really is stale?
*
* Note that for HEAD requests, we won't get the body, so for a stale
* HEAD request, we don't remove the entity - instead we let the
* CACHE_REMOVE_URL filter remove the stale item from the cache.
*/
if (cache->stale_handle) {
if (r->status == HTTP_NOT_MODIFIED) {
/* Oh, hey. It isn't that stale! Yay! */
}
else if (!r->header_only) {
/* Oh, well. Toss it. */
/* Treat the request as if it wasn't conditional. */
/*
* Restore the original request headers as they may be needed
* by further output filters like the byterange filter to make
* the correct decisions.
*/
}
}
/* no cache handle, create a new entity only for non-HEAD requests */
/* We only set info->status upon the initial creation. */
}
/* Caching layer declined the opportunity to cache the response */
}
"cache: Caching url: %s", r->unparsed_uri);
/* We are actually caching this response. So it does not
* make sense to remove this entity any more.
*/
"cache: Removing CACHE_REMOVE_URL filter.");
/*
* We now want to update the cache file header information with
* the new date, last modified, expire and content length and write
* it away to our cache file. First, we determine these values from
* the response, using heuristics if appropriate.
*
* In addition, we make HTTP/1.1 age calculations and write them away
* too.
*/
/* Read the date. Generate one if one is not supplied */
}
}
else {
}
now = apr_time_now();
/* no date header (or bad header)! */
}
/* set response_time for HTTP/1.1 age calculations */
/* get the request time */
/* check last-modified date */
/* if it's in the future, then replace by date */
r->server,
"cache: Last modified is in the future, "
"replacing with now");
}
/* if no expiry date then
* if Cache-Control: max-age
* expiry date = date + max-age
* else if lastmod
* expiry date = date + min((date - lastmod) * factor, maxexpire)
* else
* expire date = date + defaultexpire
*/
if (exp == APR_DATE_BAD) {
char *max_age_val;
max_age_val != NULL) {
apr_int64_t x;
errno = 0;
x = apr_atoi64(max_age_val);
if (errno) {
}
else {
x = x * MSEC_ONE_SEC;
}
}
}
}
/* if lastmod == date then you get 0*conf->factor which results in
* an expiration time of now. This causes some problems with
* freshness calculations, so we choose the else path...
*/
}
}
}
else {
}
}
/* We found a stale entry which wasn't really stale. */
if (cache->stale_handle) {
/* Load in the saved status and clear the status line. */
r->status_line = NULL;
/* RFC 2616 10.3.5 states that entity headers are not supposed
* to be in the 304 response. Therefore, we need to combine the
* response headers with the cached headers *before* we update
* the cached headers.
*
* However, before doing that, we need to first merge in
* err_headers_out and we also need to strip any hop-by-hop
* headers that might have snuck in.
*/
/* Merge in our cached headers. However, keep any updated values. */
}
/* Write away header information to cache. It is possible that we are
* trying to update headers for an entity which has already been cached.
*
* This may fail, due to an unwritable cache area. E.g. filesystem full,
* permissions problems or a read-only (re)mount. This must be handled
* later.
*/
/* Did we just update the cached headers on a revalidated response?
*
* If so, we can now decide what to serve to the client. This is done in
* the same way as with a regular response, but conditions are now checked
* against the cached or merged response headers.
*/
if (cache->stale_handle) {
int status;
/* Restore the original request headers and see if we need to
* return anything else than the cached response (ie. the original
* request was conditional).
*/
status = ap_meets_conditions(r);
}
else {
}
/* Before returning we need to handle the possible case of an
* unwritable cache. Rather than leaving the entity in the cache
* and having it constantly re-validated, now that we have recalled
* the body it is safe to try and remove the url from the cache.
*/
if (rv != APR_SUCCESS) {
"cache: updating headers with store_headers failed. "
"Removing cached url.");
/* Probably a mod_disk_cache cache area has been (re)mounted
* read-only, or that there is a permissions problem.
*/
"cache: attempt to remove url from cache unsuccessful.");
}
}
/* let someone else attempt to cache */
}
if (rv != APR_SUCCESS) {
"cache: store_headers failed");
}
if (rv != APR_SUCCESS) {
"cache: store_body failed");
}
/* proactively remove the lock as soon as we see the eos bucket */
/* Was this the final bucket? If yes, perform sanity checks. */
}
}
/*
* CACHE_REMOVE_URL filter
* ---------------
*
* This filter gets added in the quick handler every time the CACHE_SAVE filter
* gets inserted. Its purpose is to remove a confirmed stale cache entry from
* the cache.
*
* CACHE_REMOVE_URL has to be a protocol filter to ensure that is run even if
* the response is a canned error message, which removes the content filters
* and thus the CACHE_SAVE filter from the chain.
*
* CACHE_REMOVE_URL expects cache request rec within its context because the
* request this filter runs on can be different from the one whose cache entry
* should be removed, due to internal redirects.
*
* Note that CACHE_SAVE_URL (as a content-set filter, hence run before the
* protocol filters) will remove this filter if it decides to cache the file.
* Therefore, if this filter is left in, it must mean we need to toss any
* existing files.
*/
{
request_rec *r = f->r;
/* Setup cache_request_rec */
if (!cache) {
/* user likely configured CACHE_REMOVE_URL manually; they should really
* use mod_cache configuration to do that. So:
* 1. Remove ourselves
* 2. Do nothing and bail out
*/
"cache: CACHE_REMOVE_URL enabled unexpectedly");
}
/* Now remove this cache entry from the cache */
/* remove ourselves */
}
/* -------------------------------------------------------------- */
/* Setup configurable data */
{
const char *tmppath;
/* array of URL prefixes for which caching is enabled */
/* array of URL prefixes for which caching is disabled */
/* maximum time to cache a document */
/* default time to cache a document */
/* factor used to estimate Expires date from LastModified date */
ps->factor_set = 0;
ps->no_last_mod_ignore_set = 0;
ps->no_last_mod_ignore = 0;
ps->ignorecachecontrol = 0;
ps->ignorecachecontrol_set = 0;
ps->store_private = 0;
ps->store_private_set = 0;
ps->store_nostore = 0;
ps->store_nostore_set = 0;
/* array of headers that should not be stored in cache */
/* flag indicating that query-string should be ignored when caching */
ps->ignorequerystring = 0;
ps->ignorequerystring_set = 0;
/* array of identifiers that should not be used for key calculation */
apr_temp_dir_get(&tmppath, p);
if (tmppath) {
}
return ps;
}
{
/* array of URL prefixes for which caching is disabled */
/* array of URL prefixes for which caching is enabled */
/* maximum time to cache a document */
/* default time to cache a document */
/* factor used to estimate Expires date from LastModified date */
(overrides->no_last_mod_ignore_set == 0)
(overrides->ignorecachecontrol_set == 0)
ps->store_private =
(overrides->store_private_set == 0)
ps->store_nostore =
(overrides->store_nostore_set == 0)
ps->ignore_headers =
(overrides->ignorequerystring_set == 0)
(overrides->lockpath_set == 0)
ps->lockmaxage =
(overrides->lockmaxage_set == 0)
? base->lockmaxage
: overrides->lockmaxage;
return ps;
}
int flag)
{
conf =
&cache_module);
return NULL;
}
{
conf =
&cache_module);
return NULL;
}
int flag)
{
conf =
&cache_module);
return NULL;
}
int flag)
{
conf =
&cache_module);
return NULL;
}
const char *header)
{
char **new;
conf =
&cache_module);
/* if header None is listed clear array */
}
else {
/* Only add header if no "None" has been found in header list
* so far.
* (When 'None' is passed, IGNORE_HEADERS_SET && nelts == 0.)
*/
}
}
return NULL;
}
const char *identifier)
{
char **new;
conf =
&cache_module);
/* if identifier None is listed clear array */
}
else {
/*
* Only add identifier if no "None" has been found in identifier
* list so far.
*/
(*new) = (char *)identifier;
}
}
return NULL;
}
const char *type,
const char *url)
{
struct cache_enable *new;
if (*type == '/') {
"provider (%s) starts with a '/'. Are url and provider switched?",
type);
}
conf =
&cache_module);
return NULL;
}
} else {
}
return NULL;
}
const char *url)
{
struct cache_disable *new;
conf =
&cache_module);
return NULL;
}
} else {
}
return NULL;
}
const char *arg)
{
conf =
&cache_module);
return NULL;
}
const char *arg)
{
conf =
&cache_module);
return NULL;
}
const char *arg)
{
conf =
&cache_module);
return NULL;
}
const char *arg)
{
double val;
conf =
&cache_module);
return "CacheLastModifiedFactor value must be a float";
}
return NULL;
}
int flag)
{
conf =
&cache_module);
return NULL;
}
int flag)
{
conf =
&cache_module);
return NULL;
}
const char *arg)
{
conf =
&cache_module);
}
return NULL;
}
const char *arg)
{
conf =
&cache_module);
if (seconds <= 0) {
return "CacheLockMaxAge value must be a non-zero positive integer";
}
return NULL;
}
{
/* This is the means by which unusual (non-unix) os's may find alternate
*/
if (!cache_generate_key) {
}
return OK;
}
static const command_rec cache_cmds[] =
{
/* XXX
* Consider a new config directive that enables loading specific cache
* implememtations (like mod_cache_mem, mod_cache_file, etc.).
* Rather than using a LoadModule directive, admin would use something
* like CacheModule mem_cache_module | file_cache_module, etc,
* which would cause the approprpriate cache module to be loaded.
* This is more intuitive that requiring a LoadModule directive.
*/
"A cache type and partial URL prefix below which "
"caching is enabled"),
"A partial URL prefix below which caching is disabled"),
"The maximum time in seconds to cache a document"),
"The minimum time in seconds to cache a document"),
"The default time in seconds to cache a document"),
"Ignore Responses where there is no Last Modified Header"),
"Ignore requests from the client for uncached content"),
"Ignore 'Cache-Control: private' and store private content"),
"Ignore 'Cache-Control: no-store' and store sensitive content"),
"A space separated list of headers that should not be "
"stored by the cache"),
"Ignore query-string when caching"),
"identifiers that should be ignored for creating the key "
"of the cached entity."),
"The factor used to estimate Expires date from "
"LastModified date"),
"Enable or disable the thundering herd lock."),
"The thundering herd lock path. Defaults to the '"
DEFAULT_CACHE_LOCKPATH "' directory in the system "
"temp directory."),
"Maximum age of any thundering herd lock."),
{NULL}
};
static void register_hooks(apr_pool_t *p)
{
/* cache initializer */
/* cache handler */
/* cache filters
* XXX The cache filters need to run right after the handlers and before
* any other filters. Consider creating AP_FTYPE_CACHE for this purpose.
*
* Depending on the type of request (subrequest / main request) they
* need to be run before AP_FTYPE_CONTENT_SET / after AP_FTYPE_CONTENT_SET
* filters. Thus create two filter handles for each type:
* cache_save_filter_handle / cache_out_filter_handle to be used by
* main requests and
* cache_save_subreq_filter_handle / cache_out_subreq_filter_handle
* to be run by subrequest
*/
/*
* CACHE_SAVE must go into the filter chain after a possible DEFLATE
* filter to ensure that the compressed content is stored.
* Incrementing filter type by 1 ensures his happens.
*/
ap_register_output_filter("CACHE_SAVE",
NULL,
/*
* CACHE_SAVE_SUBREQ must go into the filter chain before SUBREQ_CORE to
* handle subrequsts. Decrementing filter type by 1 ensures this
* happens.
*/
ap_register_output_filter("CACHE_SAVE_SUBREQ",
NULL,
/*
* CACHE_OUT must go into the filter chain after a possible DEFLATE
* filter to ensure that already compressed cache objects do not
* get compressed again. Incrementing filter type by 1 ensures
* his happens.
*/
ap_register_output_filter("CACHE_OUT",
NULL,
/*
* CACHE_OUT_SUBREQ must go into the filter chain before SUBREQ_CORE to
* handle subrequsts. Decrementing filter type by 1 ensures this
* happens.
*/
ap_register_output_filter("CACHE_OUT_SUBREQ",
NULL,
/* CACHE_REMOVE_URL has to be a protocol filter to ensure that is
* run even if the response is a canned error message, which
* removes the content filters.
*/
ap_register_output_filter("CACHE_REMOVE_URL",
NULL,
}
{
NULL, /* create per-directory config structure */
NULL, /* merge per-directory config structures */
create_cache_config, /* create per-server config structure */
merge_cache_config, /* merge per-server config structures */
cache_cmds, /* command apr_table_t */
};