From: Alex Rousskov <rousskov@measurement-factory.com>
Date: Sun, 30 Jan 2011 02:21:30 +0000 (-0700)
Subject: When searching for a hit, ask each cache_dir after checking in store_table.
X-Git-Tag: take01~20^2
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=44def0f9e97f2ea527cdedb371abfc6d2b16edde;p=thirdparty%2Fsquid.git

When searching for a hit, ask each cache_dir after checking in store_table.

This allows SMP cache_dirs to share their contents without constantly worrying
about keeping the worker-specific store_table in sync among workers.
---

diff --git a/src/SwapDir.cc b/src/SwapDir.cc
index f91db78408..95fc5736f3 100644
--- a/src/SwapDir.cc
+++ b/src/SwapDir.cc
@@ -279,13 +279,11 @@ SwapDir::optionObjectSizeDump(StoreEntry * e) const
         storeAppendPrintf(e, " max-size=%"PRId64, max_objsize);
 }
 
-/* Swapdirs do not have an index of their own - thus they ask their parent..
- * but the parent child relationship isn't implemented yet
- */
+// some SwapDirs may maintain their indexes and be able to lookup an entry key
 StoreEntry *
 SwapDir::get(const cache_key *key)
 {
-    return Store::Root().get(key);
+    return NULL;
 }
 
 void
diff --git a/src/fs/rock/RockSwapDir.h b/src/fs/rock/RockSwapDir.h
index a70d21f2ee..67c5ffaf8e 100644
--- a/src/fs/rock/RockSwapDir.h
+++ b/src/fs/rock/RockSwapDir.h
@@ -24,6 +24,7 @@ public:
     /* public ::SwapDir API */
     virtual void reconfigure(int, char *);
     virtual StoreSearch *search(String const url, HttpRequest *);
+    virtual StoreEntry *get(const cache_key *key);
 
 protected:
     /* protected ::SwapDir API */
diff --git a/src/store_dir.cc b/src/store_dir.cc
index a7c90008fb..a197807bdd 100644
--- a/src/store_dir.cc
+++ b/src/store_dir.cc
@@ -691,8 +691,33 @@ StoreController::dereference(StoreEntry & e)
 StoreEntry *
 StoreController::get(const cache_key *key)
 {
+    if (StoreEntry *e = swapDir->get(key)) {
+        debugs(20, 1, HERE << "got in-transit entry: " << *e);
+        return e;
+    }
+
+    if (const int cacheDirs = Config.cacheSwap.n_configured) {
+        // ask each cache_dir until the entry is found; use static starting
+        // point to avoid asking the same subset of disks more often
+        // TODO: coordinate with put() to be able to guess the right disk often
+        static int idx = 0;
+
+        for (int n = 0; n < cacheDirs; ++n) {
+            if (idx >= cacheDirs)
+                idx = 0;
+
+            SwapDir *sd = dynamic_cast<SwapDir*>(INDEXSD(idx));
+            if (StoreEntry *e = sd->get(key)) {
+                debugs(20, 1, HERE << "cache_dir " << idx <<
+                    " got cached entry: " << *e);
+                return e;
+            }
+        }
+    }
 
-    return swapDir->get(key);
+    debugs(20, 1, HERE << "none of " << Config.cacheSwap.n_configured <<
+        " cache_dirs have " << storeKeyText(key));
+    return NULL;
 }
 
 void