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From minf...@apache.org
Subject svn commit: r1002643 - in /httpd/httpd/trunk: CHANGES modules/cache/mod_disk_cache.c modules/cache/mod_disk_cache.h
Date Wed, 29 Sep 2010 14:17:52 GMT
Author: minfrin
Date: Wed Sep 29 14:17:52 2010
New Revision: 1002643

URL: http://svn.apache.org/viewvc?rev=1002643&view=rev
Log:
mod_disk_cache: Change on-disk header file format to support the
link of the device/inode of the data file to the matching header
file, and to support the option of not writing a data file when
the data file is empty. Refactor the mod_disk_cache code so that
headers are written as late as possible (on commit), allowing the
device and inode of the body to be written to the header. At this
point, writes to the cache are now atomic, without locks.

Modified:
    httpd/httpd/trunk/CHANGES
    httpd/httpd/trunk/modules/cache/mod_disk_cache.c
    httpd/httpd/trunk/modules/cache/mod_disk_cache.h

Modified: httpd/httpd/trunk/CHANGES
URL: http://svn.apache.org/viewvc/httpd/httpd/trunk/CHANGES?rev=1002643&r1=1002642&r2=1002643&view=diff
==============================================================================
--- httpd/httpd/trunk/CHANGES [utf-8] (original)
+++ httpd/httpd/trunk/CHANGES [utf-8] Wed Sep 29 14:17:52 2010
@@ -2,6 +2,11 @@
 
 Changes with Apache 2.3.9
 
+  *) mod_disk_cache: Change on-disk header file format to support the
+     link of the device/inode of the data file to the matching header
+     file, and to support the option of not writing a data file when
+     the data file is empty. [Graham Leggett]
+
   *) core/mod_unique_id: Add generate_log_id hook to allow to use
      the ID generated by mod_unique_id as error log ID for requests.
 

Modified: httpd/httpd/trunk/modules/cache/mod_disk_cache.c
URL: http://svn.apache.org/viewvc/httpd/httpd/trunk/modules/cache/mod_disk_cache.c?rev=1002643&r1=1002642&r2=1002643&view=diff
==============================================================================
--- httpd/httpd/trunk/modules/cache/mod_disk_cache.c (original)
+++ httpd/httpd/trunk/modules/cache/mod_disk_cache.c Wed Sep 29 14:17:52 2010
@@ -219,34 +219,31 @@ static int file_cache_recall_mydata(apr_
 {
     apr_status_t rv;
     char *urlbuff;
-    disk_cache_info_t disk_info;
     apr_size_t len;
 
     /* read the data from the cache file */
     len = sizeof(disk_cache_info_t);
-    rv = apr_file_read_full(fd, &disk_info, len, &len);
+    rv = apr_file_read_full(fd, &dobj->disk_info, len, &len);
     if (rv != APR_SUCCESS) {
         return rv;
     }
 
     /* Store it away so we can get it later. */
-    dobj->disk_info = disk_info;
-
-    info->status = disk_info.status;
-    info->date = disk_info.date;
-    info->expire = disk_info.expire;
-    info->request_time = disk_info.request_time;
-    info->response_time = disk_info.response_time;
+    info->status = dobj->disk_info.status;
+    info->date = dobj->disk_info.date;
+    info->expire = dobj->disk_info.expire;
+    info->request_time = dobj->disk_info.request_time;
+    info->response_time = dobj->disk_info.response_time;
 
     /* Note that we could optimize this by conditionally doing the palloc
      * depending upon the size. */
-    urlbuff = apr_palloc(r->pool, disk_info.name_len + 1);
-    len = disk_info.name_len;
+    urlbuff = apr_palloc(r->pool, dobj->disk_info.name_len + 1);
+    len = dobj->disk_info.name_len;
     rv = apr_file_read_full(fd, urlbuff, len, &len);
     if (rv != APR_SUCCESS) {
         return rv;
     }
-    urlbuff[disk_info.name_len] = '\0';
+    urlbuff[dobj->disk_info.name_len] = '\0';
 
     /* check that we have the same URL */
     /* Would strncmp be correct? */
@@ -534,7 +531,8 @@ static int open_entity(cache_handle_t *h
         return DECLINED;
     }
 
-    rc = apr_file_info_get(&finfo, APR_FINFO_SIZE, dobj->data.fd);
+    rc = apr_file_info_get(&finfo, APR_FINFO_SIZE | APR_FINFO_IDENT,
+            dobj->data.fd);
     if (rc == APR_SUCCESS) {
         dobj->file_size = finfo.size;
     }
@@ -548,13 +546,24 @@ static int open_entity(cache_handle_t *h
         return DECLINED;
     }
 
-    /* Initialize the cache_handle callback functions */
-    ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, r->server,
-                 "disk_cache: Recalled cached URL info header %s",  dobj->name);
-
     apr_file_close(dobj->hdrs.fd);
 
-    return OK;
+    /* Atomic check - does the body file belong to the header file? */
+    if (dobj->disk_info.inode == finfo.inode && dobj->disk_info.device == finfo.device)
{
+
+        /* Initialize the cache_handle callback functions */
+        ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, r->server,
+                     "disk_cache: Recalled cached URL info header %s",  dobj->name);
+
+        return OK;
+    }
+
+    /* Oh dear, no luck matching header to the body */
+    ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, r->server,
+                 "disk_cache: Cached URL info header '%s' didn't match body, ignoring this
entry",
+                 dobj->name);
+
+    return DECLINED;
 }
 
 static int remove_entity(cache_handle_t *h)
@@ -880,6 +889,23 @@ static apr_status_t store_table(apr_file
 
 static apr_status_t store_headers(cache_handle_t *h, request_rec *r, cache_info *info)
 {
+    disk_cache_object_t *dobj = (disk_cache_object_t*) h->cache_obj->vobj;
+
+    memcpy(&h->cache_obj->info, info, sizeof(cache_info));
+
+    if (r->headers_out) {
+        dobj->headers_out = ap_cache_cacheable_headers_out(r);
+    }
+
+    if (r->headers_in) {
+        dobj->headers_in = ap_cache_cacheable_headers_in(r);
+    }
+
+    return APR_SUCCESS;
+}
+
+static apr_status_t write_headers(cache_handle_t *h, request_rec *r)
+{
     disk_cache_conf *conf = ap_get_module_config(r->server->module_config,
                                                  &disk_cache_module);
     apr_status_t rv;
@@ -889,13 +915,10 @@ static apr_status_t store_headers(cache_
     disk_cache_info_t disk_info;
     struct iovec iov[2];
 
-    /* This is flaky... we need to manage the cache_info differently */
-    h->cache_obj->info = *info;
-
-    if (r->headers_out) {
+    if (dobj->headers_out) {
         const char *tmp;
 
-        tmp = apr_table_get(r->headers_out, "Vary");
+        tmp = apr_table_get(dobj->headers_out, "Vary");
 
         if (tmp) {
             apr_array_header_t* varray;
@@ -926,8 +949,8 @@ static apr_status_t store_headers(cache_
             amt = sizeof(format);
             apr_file_write(dobj->vary.tempfd, &format, &amt);
 
-            amt = sizeof(info->expire);
-            apr_file_write(dobj->vary.tempfd, &info->expire, &amt);
+            amt = sizeof(h->cache_obj->info.expire);
+            apr_file_write(dobj->vary.tempfd, &h->cache_obj->info.expire, &amt);
 
             varray = apr_array_make(r->pool, 6, sizeof(char*));
             tokens_to_array(r->pool, tmp, varray);
@@ -936,7 +959,7 @@ static apr_status_t store_headers(cache_
 
             apr_file_close(dobj->vary.tempfd);
 
-            tmp = regen_key(r->pool, r->headers_in, varray, dobj->name);
+            tmp = regen_key(r->pool, dobj->headers_in, varray, dobj->name);
             dobj->prefix = dobj->hdrs.file;
             dobj->hashfile = NULL;
             dobj->data.file = data_file(r->pool, conf, dobj, tmp);
@@ -957,12 +980,14 @@ static apr_status_t store_headers(cache_
     }
 
     disk_info.format = DISK_FORMAT_VERSION;
-    disk_info.date = info->date;
-    disk_info.expire = info->expire;
+    disk_info.date = h->cache_obj->info.date;
+    disk_info.expire = h->cache_obj->info.expire;
     disk_info.entity_version = dobj->disk_info.entity_version++;
-    disk_info.request_time = info->request_time;
-    disk_info.response_time = info->response_time;
-    disk_info.status = info->status;
+    disk_info.request_time = h->cache_obj->info.request_time;
+    disk_info.response_time = h->cache_obj->info.response_time;
+    disk_info.status = h->cache_obj->info.status;
+    disk_info.inode = dobj->disk_info.inode;
+    disk_info.device = dobj->disk_info.device;
 
     disk_info.name_len = strlen(dobj->name);
 
@@ -980,12 +1005,8 @@ static apr_status_t store_headers(cache_
         return rv;
     }
 
-    if (r->headers_out) {
-        apr_table_t *headers_out;
-
-        headers_out = ap_cache_cacheable_headers_out(r);
-
-        rv = store_table(dobj->hdrs.tempfd, headers_out);
+    if (dobj->headers_out) {
+        rv = store_table(dobj->hdrs.tempfd, dobj->headers_out);
         if (rv != APR_SUCCESS) {
             ap_log_error(APLOG_MARK, APLOG_WARNING, rv, r->server,
                "disk_cache: could not write out-headers to header file %s",
@@ -997,12 +1018,8 @@ static apr_status_t store_headers(cache_
 
     /* Parse the vary header and dump those fields from the headers_in. */
     /* FIXME: Make call to the same thing cache_select calls to crack Vary. */
-    if (r->headers_in) {
-        apr_table_t *headers_in;
-
-        headers_in = ap_cache_cacheable_headers_in(r);
-
-        rv = store_table(dobj->hdrs.tempfd, headers_in);
+    if (dobj->headers_in) {
+        rv = store_table(dobj->hdrs.tempfd, dobj->headers_in);
         if (rv != APR_SUCCESS) {
             ap_log_error(APLOG_MARK, APLOG_WARNING, rv, r->server,
                "disk_cache: could not write in-headers to header file %s",
@@ -1032,6 +1049,7 @@ static apr_status_t store_body(cache_han
      * in file_cache_el_final().
      */
     if (!dobj->data.tempfd) {
+        apr_finfo_t finfo;
         rv = apr_file_mktemp(&dobj->data.tempfd, dobj->data.tempfile,
                              APR_CREATE | APR_WRITE | APR_BINARY |
                              APR_BUFFERED | APR_EXCL, dobj->data.pool);
@@ -1039,6 +1057,13 @@ static apr_status_t store_body(cache_han
             return rv;
         }
         dobj->file_size = 0;
+        rv = apr_file_info_get(&finfo, APR_FINFO_IDENT,
+                dobj->data.tempfd);
+        if (rv != APR_SUCCESS) {
+            return rv;
+        }
+        dobj->disk_info.device = finfo.device;
+        dobj->disk_info.inode = finfo.inode;
     }
     if (!dobj->bb) {
         dobj->bb = apr_brigade_create(r->pool, r->connection->bucket_alloc);
@@ -1199,8 +1224,13 @@ static apr_status_t commit_entity(cache_
     disk_cache_object_t *dobj = (disk_cache_object_t *) h->cache_obj->vobj;
     apr_status_t rv;
 
+    /* write the headers to disk at the last possible moment */
+    rv = write_headers(h, r);
+
     /* move header and data tempfiles to the final destination */
-    rv = file_cache_el_final(conf, &dobj->hdrs, r);
+    if (APR_SUCCESS == rv) {
+        rv = file_cache_el_final(conf, &dobj->hdrs, r);
+    }
     if (APR_SUCCESS == rv) {
         rv = file_cache_el_final(conf, &dobj->vary, r);
     }

Modified: httpd/httpd/trunk/modules/cache/mod_disk_cache.h
URL: http://svn.apache.org/viewvc/httpd/httpd/trunk/modules/cache/mod_disk_cache.h?rev=1002643&r1=1002642&r2=1002643&view=diff
==============================================================================
--- httpd/httpd/trunk/modules/cache/mod_disk_cache.h (original)
+++ httpd/httpd/trunk/modules/cache/mod_disk_cache.h Wed Sep 29 14:17:52 2010
@@ -17,12 +17,14 @@
 #ifndef MOD_DISK_CACHE_H
 #define MOD_DISK_CACHE_H
 
+#include "apr_file_io.h"
+
 /*
  * include for mod_disk_cache: Disk Based HTTP 1.1 Cache.
  */
 
-#define VARY_FORMAT_VERSION 3
-#define DISK_FORMAT_VERSION 4
+#define VARY_FORMAT_VERSION 5
+#define DISK_FORMAT_VERSION 6
 
 #define CACHE_HEADER_SUFFIX ".header"
 #define CACHE_DATA_SUFFIX   ".data"
@@ -49,6 +51,12 @@ typedef struct {
     apr_time_t expire;
     apr_time_t request_time;
     apr_time_t response_time;
+    /* The ident of the body file, so we can test the body matches the header */
+    apr_ino_t inode;
+    apr_dev_t device;
+    /* Does this cached request have a body? */
+    int has_body;
+    int header_only;
 } disk_cache_info_t;
 
 typedef struct {
@@ -76,6 +84,8 @@ typedef struct disk_cache_object {
     apr_off_t file_size;         /*  File size of the cached data file  */
     disk_cache_info_t disk_info; /* Header information. */
     apr_bucket_brigade *bb;      /* Set aside brigade */
+    apr_table_t *headers_in;     /* Input headers to save */
+    apr_table_t *headers_out;    /* Output headers to save */
     apr_off_t offset;            /* Max size to set aside */
     apr_time_t timeout;          /* Max time to set aside */
     int done;                    /* Is the attempt to cache complete? */



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