1 files changed, 143 insertions, 0 deletions
diff --git a/mobile/android/thirdparty/ch/boye/httpclientandroidlib/impl/client/cache/DefaultFailureCache.java b/mobile/android/thirdparty/ch/boye/httpclientandroidlib/impl/client/cache/DefaultFailureCache.java
new file mode 100644
index 000000000..3646c3c32
--- /dev/null
+++ b/mobile/android/thirdparty/ch/boye/httpclientandroidlib/impl/client/cache/DefaultFailureCache.java
@@ -0,0 +1,143 @@
+/*
+ * ====================================================================
+ * 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.
+ * ====================================================================
+ *
+ * This software consists of voluntary contributions made by many
+ * individuals on behalf of the Apache Software Foundation.  For more
+ * information on the Apache Software Foundation, please see
+ * <http://www.apache.org/>.
+ *
+ */
+package ch.boye.httpclientandroidlib.impl.client.cache;
+
+import ch.boye.httpclientandroidlib.annotation.ThreadSafe;
+
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ConcurrentMap;
+
+/**
+ * Implements a bounded failure cache. The oldest entries are discarded when
+ * the maximum size is exceeded.
+ *
+ * @since 4.3
+ */
+@ThreadSafe
+public class DefaultFailureCache implements FailureCache {
+
+    static final int DEFAULT_MAX_SIZE = 1000;
+    static final int MAX_UPDATE_TRIES = 10;
+
+    private final int maxSize;
+    private final ConcurrentMap<String, FailureCacheValue> storage;
+
+    /**
+     * Create a new failure cache with the maximum size of
+     * {@link #DEFAULT_MAX_SIZE}.
+     */
+    public DefaultFailureCache() {
+        this(DEFAULT_MAX_SIZE);
+    }
+
+    /**
+     * Creates a new failure cache with the specified maximum size.
+     * @param maxSize the maximum number of entries the cache should store
+     */
+    public DefaultFailureCache(final int maxSize) {
+        this.maxSize = maxSize;
+        this.storage = new ConcurrentHashMap<String, FailureCacheValue>();
+    }
+
+    public int getErrorCount(final String identifier) {
+        if (identifier == null) {
+            throw new IllegalArgumentException("identifier may not be null");
+        }
+        final FailureCacheValue storedErrorCode = storage.get(identifier);
+        return storedErrorCode != null ? storedErrorCode.getErrorCount() : 0;
+    }
+
+    public void resetErrorCount(final String identifier) {
+        if (identifier == null) {
+            throw new IllegalArgumentException("identifier may not be null");
+        }
+        storage.remove(identifier);
+    }
+
+    public void increaseErrorCount(final String identifier) {
+        if (identifier == null) {
+            throw new IllegalArgumentException("identifier may not be null");
+        }
+        updateValue(identifier);
+        removeOldestEntryIfMapSizeExceeded();
+    }
+
+    private void updateValue(final String identifier) {
+        /**
+         * Due to concurrency it is possible that someone else is modifying an
+         * entry before we could write back our updated value. So we keep
+         * trying until it is our turn.
+         *
+         * In case there is a lot of contention on that identifier, a thread
+         * might starve. Thus it gives up after a certain number of failed
+         * update tries.
+         */
+        for (int i = 0; i < MAX_UPDATE_TRIES; i++) {
+            final FailureCacheValue oldValue = storage.get(identifier);
+            if (oldValue == null) {
+                final FailureCacheValue newValue = new FailureCacheValue(identifier, 1);
+                if (storage.putIfAbsent(identifier, newValue) == null) {
+                    return;
+                }
+            }
+            else {
+                final int errorCount = oldValue.getErrorCount();
+                if (errorCount == Integer.MAX_VALUE) {
+                    return;
+                }
+                final FailureCacheValue newValue = new FailureCacheValue(identifier, errorCount + 1);
+                if (storage.replace(identifier, oldValue, newValue)) {
+                    return;
+                }
+            }
+        }
+    }
+
+    private void removeOldestEntryIfMapSizeExceeded() {
+        if (storage.size() > maxSize) {
+            final FailureCacheValue valueWithOldestTimestamp = findValueWithOldestTimestamp();
+            if (valueWithOldestTimestamp != null) {
+                storage.remove(valueWithOldestTimestamp.getKey(), valueWithOldestTimestamp);
+            }
+        }
+    }
+
+    private FailureCacheValue findValueWithOldestTimestamp() {
+        long oldestTimestamp = Long.MAX_VALUE;
+        FailureCacheValue oldestValue = null;
+        for (final Map.Entry<String, FailureCacheValue> storageEntry : storage.entrySet()) {
+            final FailureCacheValue value = storageEntry.getValue();
+            final long creationTimeInNanos = value.getCreationTimeInNanos();
+            if (creationTimeInNanos < oldestTimestamp) {
+                oldestTimestamp = creationTimeInNanos;
+                oldestValue = storageEntry.getValue();
+            }
+        }
+        return oldestValue;
+    }
+}