Author: fhanik
Date: Fri Jul 10 16:25:14 2009
New Revision: 793017
URL: http://svn.apache.org/viewvc?rev=793017&view=rev
Log:
Added some comments and more thread safety around the size of the pool
Modified:
tomcat/trunk/modules/jdbc-pool/java/org/apache/tomcat/jdbc/pool/ConnectionPool.java
tomcat/trunk/modules/jdbc-pool/java/org/apache/tomcat/jdbc/pool/PooledConnection.java
Modified:
tomcat/trunk/modules/jdbc-pool/java/org/apache/tomcat/jdbc/pool/ConnectionPool.java
URL:
http://svn.apache.org/viewvc/tomcat/trunk/modules/jdbc-pool/java/org/apache/tomcat/jdbc/pool/ConnectionPool.java?rev=793017&r1=793016&r2=793017&view=diff
==============================================================================
---
tomcat/trunk/modules/jdbc-pool/java/org/apache/tomcat/jdbc/pool/ConnectionPool.java
(original)
+++
tomcat/trunk/modules/jdbc-pool/java/org/apache/tomcat/jdbc/pool/ConnectionPool.java
Fri Jul 10 16:25:14 2009
@@ -450,7 +450,7 @@
//===============================================================================
-// CONNECTION POOLING IMPL
+// CONNECTION POOLING IMPL LOGIC
//===============================================================================
/**
@@ -471,6 +471,7 @@
if (jmxPool!=null) {
jmxPool.notify(org.apache.tomcat.jdbc.pool.jmx.ConnectionPool.NOTIFY_ABANDON,
trace);
}
+ //release the connection
release(con);
//we've asynchronously reduced the number of connections
//we could have threads stuck in idle.poll(timeout) that will
never be notified
@@ -490,10 +491,10 @@
try {
con.lock();
if (con.release()) {
+ //counter only decremented once
size.addAndGet(-1);
}
} finally {
-
con.unlock();
}
}
@@ -518,9 +519,9 @@
while (true) {
if (con!=null) {
+ //configure the connection and return it
PooledConnection result = borrowConnection(now, con);
- //validation might have failed, in which case null is returned
- //should not happen anymore
+ //null should never be returned, but was in a previous impl.
if (result!=null) return result;
}
@@ -529,15 +530,22 @@
//atomic variable - a connection can become idle while we are
creating
//a new connection
if (size.get() < getPoolProperties().getMaxActive()) {
- size.addAndGet(1);
- return createConnection(now, con);
+ //atomic duplicate check
+ if (size.addAndGet(1) > getPoolProperties().getMaxActive()) {
+ return createConnection(now, con);
+ } else {
+ //if we got here, two threads passed through the first if
+ size.decrementAndGet();
+ }
} //end if
//calculate wait time for this iteration
long maxWait = wait;
+ //if the passed in wait time is -1, means we should use the pool
property value
if (wait==-1) {
maxWait =
(getPoolProperties().getMaxWait()<=0)?Long.MAX_VALUE:getPoolProperties().getMaxWait();
}
+
long timetowait = Math.max(0, maxWait -
(System.currentTimeMillis() - now));
waitcount.incrementAndGet();
try {
@@ -614,10 +622,13 @@
protected PooledConnection borrowConnection(long now, PooledConnection
con) throws SQLException {
//we have a connection, lets set it up
+
+ //flag to see if we need to nullify
boolean setToNull = false;
try {
con.lock();
if (!con.isDiscarded() && !con.isInitialized()) {
+ //attempt to connect
con.connect();
}
if ((!con.isDiscarded()) &&
con.validate(PooledConnection.VALIDATE_BORROW)) {
Modified:
tomcat/trunk/modules/jdbc-pool/java/org/apache/tomcat/jdbc/pool/PooledConnection.java
URL:
http://svn.apache.org/viewvc/tomcat/trunk/modules/jdbc-pool/java/org/apache/tomcat/jdbc/pool/PooledConnection.java?rev=793017&r1=793016&r2=793017&view=diff
==============================================================================
---
tomcat/trunk/modules/jdbc-pool/java/org/apache/tomcat/jdbc/pool/PooledConnection.java
(original)
+++
tomcat/trunk/modules/jdbc-pool/java/org/apache/tomcat/jdbc/pool/PooledConnection.java
Fri Jul 10 16:25:14 2009
@@ -85,7 +85,7 @@
/**
* Set to true if this connection has been discarded by the pool
*/
- private boolean discarded = false;
+ private volatile boolean discarded = false;
/**
* The Timestamp when the last time the connect() method was called
successfully
*/
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