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java/org/apache/coyote/http2/AbstractStream.java

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+/*
+ *  Licensed to the Apache Software Foundation (ASF) under one or more
+ *  contributor license agreements.  See the NOTICE file distributed with
+ *  this work for additional information regarding copyright ownership.
+ *  The ASF licenses this file to You 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.apache.coyote.http2;
+
+import java.util.Collections;
+import java.util.Set;
+import java.util.concurrent.ConcurrentHashMap;
+
+import org.apache.juli.logging.Log;
+import org.apache.juli.logging.LogFactory;
+import org.apache.tomcat.util.res.StringManager;
+
+/**
+ * Used to managed prioritisation.
+ */
+abstract class AbstractStream {
+
+    private static final Log log = LogFactory.getLog(AbstractStream.class);
+    private static final StringManager sm = StringManager.getManager(AbstractStream.class);
+
+    private final Integer identifier;
+
+    private volatile AbstractStream parentStream = null;
+    private final Set<Stream> childStreams =
+            Collections.newSetFromMap(new ConcurrentHashMap<Stream,Boolean>());
+    private long windowSize = ConnectionSettingsBase.DEFAULT_INITIAL_WINDOW_SIZE;
+
+
+    public AbstractStream(Integer identifier) {
+        this.identifier = identifier;
+    }
+
+
+    public Integer getIdentifier() {
+        return identifier;
+    }
+
+
+    public int getIdAsInt() {
+        return identifier.intValue();
+    }
+
+
+    void detachFromParent() {
+        if (parentStream != null) {
+            parentStream.getChildStreams().remove(this);
+            parentStream = null;
+        }
+    }
+
+
+    final void addChild(Stream child) {
+        child.setParentStream(this);
+        childStreams.add(child);
+    }
+
+
+    boolean isDescendant(AbstractStream stream) {
+        // Is the passed in Stream a descendant of this Stream?
+        // Start at the passed in Stream and work up
+        AbstractStream parent = stream.getParentStream();
+        while (parent != null && parent != this) {
+            parent = parent.getParentStream();
+        }
+        return parent != null;
+    }
+
+
+    AbstractStream getParentStream() {
+        return parentStream;
+    }
+
+
+    void setParentStream(AbstractStream parentStream) {
+        this.parentStream = parentStream;
+    }
+
+
+    final Set<Stream> getChildStreams() {
+        return childStreams;
+    }
+
+
+    protected synchronized void setWindowSize(long windowSize) {
+        this.windowSize = windowSize;
+    }
+
+
+    protected synchronized long getWindowSize() {
+        return windowSize;
+    }
+
+
+    /**
+     * Increment window size.
+     * @param increment The amount by which the window size should be increased
+     * @throws Http2Exception If the window size is now higher than
+     *  the maximum allowed
+     */
+    protected synchronized void incrementWindowSize(int increment) throws Http2Exception {
+        // No need for overflow protection here.
+        // Increment can't be more than Integer.MAX_VALUE and once windowSize
+        // goes beyond 2^31-1 an error is triggered.
+        windowSize += increment;
+
+        if (log.isDebugEnabled()) {
+            log.debug(sm.getString("abstractStream.windowSizeInc", getConnectionId(),
+                    getIdentifier(), Integer.toString(increment), Long.toString(windowSize)));
+        }
+
+        if (windowSize > ConnectionSettingsBase.MAX_WINDOW_SIZE) {
+            String msg = sm.getString("abstractStream.windowSizeTooBig", getConnectionId(), identifier,
+                    Integer.toString(increment), Long.toString(windowSize));
+            if (identifier.intValue() == 0) {
+                throw new ConnectionException(msg, Http2Error.FLOW_CONTROL_ERROR);
+            } else {
+                throw new StreamException(
+                        msg, Http2Error.FLOW_CONTROL_ERROR, identifier.intValue());
+            }
+        }
+    }
+
+
+    protected synchronized void decrementWindowSize(int decrement) {
+        // No need for overflow protection here. Decrement can never be larger
+        // the Integer.MAX_VALUE and once windowSize goes negative no further
+        // decrements are permitted
+        windowSize -= decrement;
+        if (log.isDebugEnabled()) {
+            log.debug(sm.getString("abstractStream.windowSizeDec", getConnectionId(),
+                    getIdentifier(), Integer.toString(decrement), Long.toString(windowSize)));
+        }
+    }
+
+
+    protected abstract String getConnectionId();
+
+    protected abstract int getWeight();
+
+    @Deprecated // Unused
+    protected abstract void doNotifyAll();
+}