pt 1 in reviving the android build (copied from pm 28a1, wish me luck)

mobile/android/thirdparty/ch/boye/httpclientandroidlib/impl/client/AIMDBackoffManager.java

@@ -0,0 +1,164 @@
+/*
+ * ====================================================================
+ * 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;
+
+import java.util.HashMap;
+import java.util.Map;
+
+import ch.boye.httpclientandroidlib.client.BackoffManager;
+import ch.boye.httpclientandroidlib.conn.routing.HttpRoute;
+import ch.boye.httpclientandroidlib.pool.ConnPoolControl;
+import ch.boye.httpclientandroidlib.util.Args;
+
+/**
+ * <p>The <code>AIMDBackoffManager</code> applies an additive increase,
+ * multiplicative decrease (AIMD) to managing a dynamic limit to
+ * the number of connections allowed to a given host. You may want
+ * to experiment with the settings for the cooldown periods and the
+ * backoff factor to get the adaptive behavior you want.</p>
+ *
+ * <p>Generally speaking, shorter cooldowns will lead to more steady-state
+ * variability but faster reaction times, while longer cooldowns
+ * will lead to more stable equilibrium behavior but slower reaction
+ * times.</p>
+ *
+ * <p>Similarly, higher backoff factors promote greater
+ * utilization of available capacity at the expense of fairness
+ * among clients. Lower backoff factors allow equal distribution of
+ * capacity among clients (fairness) to happen faster, at the
+ * expense of having more server capacity unused in the short term.</p>
+ *
+ * @since 4.2
+ */
+public class AIMDBackoffManager implements BackoffManager {
+
+    private final ConnPoolControl<HttpRoute> connPerRoute;
+    private final Clock clock;
+    private final Map<HttpRoute,Long> lastRouteProbes;
+    private final Map<HttpRoute,Long> lastRouteBackoffs;
+    private long coolDown = 5 * 1000L;
+    private double backoffFactor = 0.5;
+    private int cap = 2; // Per RFC 2616 sec 8.1.4
+
+    /**
+     * Creates an <code>AIMDBackoffManager</code> to manage
+     * per-host connection pool sizes represented by the
+     * given {@link ConnPoolControl}.
+     * @param connPerRoute per-host routing maximums to
+     *   be managed
+     */
+    public AIMDBackoffManager(final ConnPoolControl<HttpRoute> connPerRoute) {
+        this(connPerRoute, new SystemClock());
+    }
+
+    AIMDBackoffManager(final ConnPoolControl<HttpRoute> connPerRoute, final Clock clock) {
+        this.clock = clock;
+        this.connPerRoute = connPerRoute;
+        this.lastRouteProbes = new HashMap<HttpRoute,Long>();
+        this.lastRouteBackoffs = new HashMap<HttpRoute,Long>();
+    }
+
+    public void backOff(final HttpRoute route) {
+        synchronized(connPerRoute) {
+            final int curr = connPerRoute.getMaxPerRoute(route);
+            final Long lastUpdate = getLastUpdate(lastRouteBackoffs, route);
+            final long now = clock.getCurrentTime();
+            if (now - lastUpdate.longValue() < coolDown) {
+                return;
+            }
+            connPerRoute.setMaxPerRoute(route, getBackedOffPoolSize(curr));
+            lastRouteBackoffs.put(route, Long.valueOf(now));
+        }
+    }
+
+    private int getBackedOffPoolSize(final int curr) {
+        if (curr <= 1) {
+            return 1;
+        }
+        return (int)(Math.floor(backoffFactor * curr));
+    }
+
+    public void probe(final HttpRoute route) {
+        synchronized(connPerRoute) {
+            final int curr = connPerRoute.getMaxPerRoute(route);
+            final int max = (curr >= cap) ? cap : curr + 1;
+            final Long lastProbe = getLastUpdate(lastRouteProbes, route);
+            final Long lastBackoff = getLastUpdate(lastRouteBackoffs, route);
+            final long now = clock.getCurrentTime();
+            if (now - lastProbe.longValue() < coolDown || now - lastBackoff.longValue() < coolDown) {
+                return;
+            }
+            connPerRoute.setMaxPerRoute(route, max);
+            lastRouteProbes.put(route, Long.valueOf(now));
+        }
+    }
+
+    private Long getLastUpdate(final Map<HttpRoute,Long> updates, final HttpRoute route) {
+        Long lastUpdate = updates.get(route);
+        if (lastUpdate == null) {
+            lastUpdate = Long.valueOf(0L);
+        }
+        return lastUpdate;
+    }
+
+    /**
+     * Sets the factor to use when backing off; the new
+     * per-host limit will be roughly the current max times
+     * this factor. <code>Math.floor</code> is applied in the
+     * case of non-integer outcomes to ensure we actually
+     * decrease the pool size. Pool sizes are never decreased
+     * below 1, however. Defaults to 0.5.
+     * @param d must be between 0.0 and 1.0, exclusive.
+     */
+    public void setBackoffFactor(final double d) {
+        Args.check(d > 0.0 && d < 1.0, "Backoff factor must be 0.0 < f < 1.0");
+        backoffFactor = d;
+    }
+
+    /**
+     * Sets the amount of time, in milliseconds, to wait between
+     * adjustments in pool sizes for a given host, to allow
+     * enough time for the adjustments to take effect. Defaults
+     * to 5000L (5 seconds).
+     * @param l must be positive
+     */
+    public void setCooldownMillis(final long l) {
+        Args.positive(coolDown, "Cool down");
+        coolDown = l;
+    }
+
+    /**
+     * Sets the absolute maximum per-host connection pool size to
+     * probe up to; defaults to 2 (the default per-host max).
+     * @param cap must be >= 1
+     */
+    public void setPerHostConnectionCap(final int cap) {
+        Args.positive(cap, "Per host connection cap");
+        this.cap = cap;
+    }
+
+}