Pull cacheinvalidations code directory into chromium repo.

third_party/cacheinvalidation/src/google/cacheinvalidation/impl/exponential-backoff-delay-generator.h

Index: third_party/cacheinvalidation/src/google/cacheinvalidation/impl/exponential-backoff-delay-generator.h
diff --git a/third_party/cacheinvalidation/src/google/cacheinvalidation/impl/exponential-backoff-delay-generator.h b/third_party/cacheinvalidation/src/google/cacheinvalidation/impl/exponential-backoff-delay-generator.h
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@@ -0,0 +1,79 @@
+// Copyright 2012 Google Inc.
+//
+// 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.
+
+// Class that generates successive intervals for random exponential backoff.
+// Class tracks a "high water mark" which is doubled each time getNextDelay is
+// called; each call to getNextDelay returns a value uniformly randomly
+// distributed between 0 (inclusive) and the high water mark (exclusive). Note
+// that this class does not dictate the time units for which the delay is
+// computed.
+
+#ifndef GOOGLE_CACHEINVALIDATION_IMPL_EXPONENTIAL_BACKOFF_DELAY_GENERATOR_H_
+#define GOOGLE_CACHEINVALIDATION_IMPL_EXPONENTIAL_BACKOFF_DELAY_GENERATOR_H_
+
+#include "google/cacheinvalidation/include/system-resources.h"
+#include "google/cacheinvalidation/deps/scoped_ptr.h"
+#include "google/cacheinvalidation/deps/logging.h"
+#include "google/cacheinvalidation/deps/time.h"
+#include "google/cacheinvalidation/deps/random.h"
+#include "google/cacheinvalidation/impl/constants.h"
+
+namespace invalidation {
+
+class ExponentialBackoffDelayGenerator {
+ public:
+  /* Creates a generator with the given maximum and initial delays.
+   * Caller continues to own space for random.
+   */
+  ExponentialBackoffDelayGenerator(Random* random, TimeDelta initial_max_delay,
+                                   int max_exponential_factor) :
+    initial_max_delay_(initial_max_delay),
+    max_exponential_factor_(max_exponential_factor), random_(random) {
+    CHECK_GT(max_exponential_factor_, 0) << "max factor must be positive";
+    CHECK(random_ != NULL);
+    CHECK(initial_max_delay > Scheduler::NoDelay()) <<
+        "Initial delay must be positive";
+    Reset();
+  }
+
+  /* Resets the exponential backoff generator to start delays at the initial
+   * delay.
+   */
+  void Reset() {
+    current_max_delay_ = initial_max_delay_;
+    in_retry_mode = false;
+  }
+
+  /* Gets the next delay interval to use. */
+  TimeDelta GetNextDelay();
+
+ private:
+  /* Initial delay time to use. */
+  TimeDelta initial_max_delay_;
+
+  /* Maximum allowed delay time. */
+  int max_exponential_factor_;
+
+  /* Next delay time to use. */
+  TimeDelta current_max_delay_;
+
+  /* If the first call to getNextDelay has been made after reset. */
+  bool in_retry_mode;
+
+  Random* random_;
+};
+
+}  // namespace invalidation
+
+#endif  // GOOGLE_CACHEINVALIDATION_IMPL_EXPONENTIAL_BACKOFF_DELAY_GENERATOR_H_