1 files changed, 48 insertions, 0 deletions
diff --git a/bundles/org.eclipse.equinox.logstream/src/org/osgi/util/pushstream/PushbackPolicy.java b/bundles/org.eclipse.equinox.logstream/src/org/osgi/util/pushstream/PushbackPolicy.java
new file mode 100644
index 000000000..4f7f1864f
--- /dev/null
+++ b/bundles/org.eclipse.equinox.logstream/src/org/osgi/util/pushstream/PushbackPolicy.java
@@ -0,0 +1,48 @@
+/*
+ * Copyright (c) OSGi Alliance (2015, 2016). All Rights Reserved.
+ * 
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.osgi.util.pushstream;
+
+import java.util.concurrent.BlockingQueue;
+import org.osgi.annotation.versioning.ConsumerType;
+
+/**
+ * A {@link PushbackPolicy} is used to calculate how much back pressure to apply
+ * based on the current buffer. The {@link PushbackPolicy} will be called after
+ * an event has been queued, and the returned value will be used as back
+ * pressure.
+ * 
+ * @see PushbackPolicyOption
+ * 
+ *
+ * @param <T> The type of the data
+ * @param <U> The type of the queue
+ */
+@ConsumerType
+@FunctionalInterface
+public interface PushbackPolicy<T, U extends BlockingQueue<PushEvent<? extends T>>> {
+	
+	/**
+	 * Given the current state of the queue, determine the level of back
+	 * pressure that should be applied
+	 * 
+	 * @param queue
+	 * @return a back pressure value in nanoseconds
+	 * @throws Exception
+	 */
+	public long pushback(U queue) throws Exception;
+	
+}