theanti9 · July 31, 2014 06:51 · Jul 31, 2014
diff --git a/ConnectionPool.scala b/ConnectionPool.scala
@@ -0,0 +1,44 @@
+import java.util.concurrent.BlockingQueue
+import java.util.concurrent.LinkedBlockingQueue
+import java.util.concurrent.TimeUnit
+
+class MaxLeaseRetriesException(message:String = null, cause:Throwable = null) extends Exception(message, cause)
+
+class ConnectionPool[R](maxSize:Int, timeout:Int = 1000, unit: TimeUnit = TimeUnit.MILLISECONDS) {
+
+  val q: BlockingQueue[R] = new LinkedBlockingQueue[R](maxSize) 
+
+  /**
+   * Given an initialization block, fill the connection pool.
+   */
+  def construct(block: ()=> R) {
+	for (_ <- 0 to maxSize) {
+	  q.put(block())
+	}
+  }
+
+  /**
+   * Lease a connection from the pool for the duration of a code block
+   * Use the default timeout to try and acquire the lease. Retry `maxRetries` times
+   * to acquire the lease.
+   * 
+   * Throws a MaxLeaseRetriesException if the maxRetries is hit with no luck.
+   */
+  def lease[T](block: R => T, maxRetries:Int=10): T = {
+    var con:R = q.poll(timeout, unit)
+    var tries:Int = 1
+
+    while (con == null && tries <= maxRetries) { 
+      con = q.poll(timeout, unit)
+      tries+=1
+    }
+
+    if (con == null) {
+      throw new MaxLeaseRetriesException(s"Tried to acquire connection lease ${maxRetries} times with no success!")
+    }
+
+    val result = block(con)
+    q.put(con)
+    result
+  }
+}
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