rpc: make gettxoutsettinfo run lock-free

laanwj · laanwj · commit 57092ed9e7ed · 2015-06-16T13:50:38.000+02:00
For leveldb "An iterator operates on a snapshot of the database taken
when the iterator is created". This means that it is unnecessary to
lock out other threads while computing statistics, and neither to hold
cs_main for the whole time. Let the thread run free.
diff --git a/src/rpcblockchain.cpp b/src/rpcblockchain.cpp
@@ -345,8 +345,6 @@ UniValue gettxoutsetinfo(const UniValue& params, bool fHelp)
             + HelpExampleRpc("gettxoutsetinfo", "")
         );
 
-    LOCK(cs_main);
-
     UniValue ret(UniValue::VOBJ);
 
     CCoinsStats stats;
diff --git a/src/txdb.cpp b/src/txdb.cpp
@@ -147,7 +147,10 @@ bool CCoinsViewDB::GetStats(CCoinsStats &stats) const {
             return error("%s: Deserialize or I/O error - %s", __func__, e.what());
         }
     }
-    stats.nHeight = mapBlockIndex.find(GetBestBlock())->second->nHeight;
+    {
+        LOCK(cs_main);
+        stats.nHeight = mapBlockIndex.find(stats.hashBlock)->second->nHeight;
+    }
     stats.hashSerialized = ss.GetHash();
     stats.nTotalAmount = nTotalAmount;
     return true;

Original file line number	Diff line number	Diff line change
`@@ -147,7 +147,10 @@ bool CCoinsViewDB::GetStats(CCoinsStats &stats) const {`
`147`	`147`	`return error("%s: Deserialize or I/O error - %s", __func__, e.what());`
`148`	`148`	`}`
`149`	`149`	`}`
`150`		`- stats.nHeight = mapBlockIndex.find(GetBestBlock())->second->nHeight;`
	`150`	`+ {`
	`151`	`+ LOCK(cs_main);`
	`152`	`+ stats.nHeight = mapBlockIndex.find(stats.hashBlock)->second->nHeight;`
	`153`	`+ }`
`151`	`154`	`stats.hashSerialized = ss.GetHash();`
`152`	`155`	`stats.nTotalAmount = nTotalAmount;`
`153`	`156`	`return true;`