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Unified Diff: net/base/backoff_entry.h

Issue 6696023: Remove minidump analysis aides from URLRequestThrottlerManager. New (Closed) Base URL: svn://svn.chromium.org/chrome/trunk/src
Patch Set: Created 9 years, 9 months ago
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Index: net/base/backoff_entry.h
diff --git a/net/base/backoff_entry.h b/net/base/backoff_entry.h
new file mode 100644
index 0000000000000000000000000000000000000000..a95b567b1ae76112a0a7290ea56d61077be7a0f4
--- /dev/null
+++ b/net/base/backoff_entry.h
@@ -0,0 +1,96 @@
+// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef NET_BASE_BACKOFF_ITEM_H_
+#define NET_BASE_BACKOFF_ITEM_H_
+#pragma once
+
+#include "base/threading/non_thread_safe.h"
+#include "base/time.h"
+
+namespace net {
+
+// Provides the core logic needed for randomized exponential back-off
+// on requests to a given resource, given a back-off policy.
+//
+// This utility class knows nothing about network specifics; it is
+// intended for reuse in various networking scenarios.
+class BackoffEntry : public base::NonThreadSafe {
+ public:
+
+ // The set of parameters that define a back-off policy.
+ struct Policy {
+ // Number of initial errors (in sequence) to ignore before applying
+ // exponential back-off rules.
+ int num_errors_to_ignore_;
+
+ // Initial delay for exponential back-off.
+ int initial_backoff_ms_;
+
+ // Factor by which the waiting time will be multiplied.
+ double multiply_factor_;
+
+ // Fuzzing percentage. ex: 10% will spread requests randomly
+ // between 90%-100% of the calculated time.
+ double jitter_factor_;
+
+ // Maximum amount of time we are willing to delay our request.
+ int maximum_backoff_ms_;
+
+ // Time to keep an entry from being discarded even when it
+ // has no significant state, -1 to never discard.
+ int entry_lifetime_ms_;
+ };
+
+ // Lifetime of policy must enclose lifetime of BackoffEntry. The
+ // pointer must be valid but is not dereferenced during construction.
+ BackoffEntry(const Policy* policy);
+ ~BackoffEntry();
+
+ // Inform this item that a request for the network resource it is
+ // tracking was made, and whether it failed or succeeded.
+ void InformOfRequest(bool succeeded);
+
+ // Returns true if a request for the resource this item tracks should
+ // be rejected at the present time due to exponential backoff policy.
+ bool ShouldRejectRequest() const;
+
+ // Returns the absolute time after which this entry (given its present
+ // state) will no longer reject requests.
+ base::TimeTicks GetReleaseTime() const;
+
+ // Causes this object reject requests until the specified absolute time.
+ // This can be used to e.g. implement support for a Retry-After header.
+ void SetCustomReleaseTime(const base::TimeTicks release_time);
+
+ // Returns true if this object has no significant state (i.e. you could
+ // just as well start with a fresh BackoffEntry object), and hasn't
+ // had for Policy::entry_lifetime_ms_.
+ bool CanDiscard() const;
+
+ protected:
+
+ // Equivalent to TimeTicks::Now(), virtual so unit tests can override.
+ virtual base::TimeTicks GetTimeNow() const;
+
+ // Calculates when requests should again be allowed through.
+ base::TimeTicks CalculateReleaseTime() const;
+
+ private:
+
+ // Timestamp calculated by the exponential back-off algorithm at which we are
+ // allowed to start sending requests again.
+ base::TimeTicks exponential_backoff_release_time_;
+
+ // Counts request errors; reset on success.
+ int failure_count_;
+
+ const Policy* policy_;
+
+ DISALLOW_COPY_AND_ASSIGN(BackoffEntry);
+};
+
+} // namespace net
+
+#endif // NET_BASE_BACKOFF_ITEM_H_
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