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- // Copyright (c) 2012 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.
- #include "components/sync/engine/backoff_delay_provider.h"
- #include <stdint.h>
- #include <algorithm>
- #include "base/memory/ptr_util.h"
- #include "base/rand_util.h"
- #include "components/sync/base/syncer_error.h"
- #include "components/sync/engine/cycle/model_neutral_state.h"
- #include "components/sync/engine/polling_constants.h"
- namespace syncer {
- namespace {
- // This calculates approx. last_delay * kBackoffMultiplyFactor +/- last_delay
- // * kBackoffJitterFactor. |jitter_sign| must be -1 or 1 and determines whether
- // the jitter in the delay will be positive or negative.
- base::TimeDelta GetDelayImpl(base::TimeDelta last_delay, int jitter_sign) {
- DCHECK(jitter_sign == -1 || jitter_sign == 1);
- if (last_delay >= kMaxBackoffTime)
- return kMaxBackoffTime;
- const base::TimeDelta backoff =
- std::max(kMinBackoffTime, last_delay * kBackoffMultiplyFactor) +
- jitter_sign * kBackoffJitterFactor * last_delay;
- // Clamp backoff between 1 second and |kMaxBackoffTime|.
- return std::max(kMinBackoffTime, std::min(backoff, kMaxBackoffTime));
- }
- } // namespace
- // static
- std::unique_ptr<BackoffDelayProvider> BackoffDelayProvider::FromDefaults() {
- // base::WrapUnique() used because the constructor is private.
- return base::WrapUnique(new BackoffDelayProvider(
- kInitialBackoffRetryTime, kInitialBackoffImmediateRetryTime));
- }
- // static
- std::unique_ptr<BackoffDelayProvider>
- BackoffDelayProvider::WithShortInitialRetryOverride() {
- // base::WrapUnique() used because the constructor is private.
- return base::WrapUnique(new BackoffDelayProvider(
- kInitialBackoffShortRetryTime, kInitialBackoffImmediateRetryTime));
- }
- BackoffDelayProvider::BackoffDelayProvider(
- const base::TimeDelta& default_initial_backoff,
- const base::TimeDelta& short_initial_backoff)
- : default_initial_backoff_(default_initial_backoff),
- short_initial_backoff_(short_initial_backoff) {}
- BackoffDelayProvider::~BackoffDelayProvider() = default;
- base::TimeDelta BackoffDelayProvider::GetDelay(
- const base::TimeDelta& last_delay) {
- // Flip a coin to randomize backoff interval by +/- kBackoffJitterFactor.
- const int jitter_sign = base::RandInt(0, 1) * 2 - 1;
- return GetDelayImpl(last_delay, jitter_sign);
- }
- base::TimeDelta BackoffDelayProvider::GetInitialDelay(
- const ModelNeutralState& state) const {
- // NETWORK_CONNECTION_UNAVAILABLE implies we did not receive HTTP response
- // from server because of some network error. If network is unavailable then
- // on next connection type or address change scheduler will run canary job.
- // Otherwise we'll retry in 30 seconds.
- if (state.commit_result.value() ==
- SyncerError::NETWORK_CONNECTION_UNAVAILABLE ||
- state.last_download_updates_result.value() ==
- SyncerError::NETWORK_CONNECTION_UNAVAILABLE) {
- return default_initial_backoff_;
- }
- if (state.last_get_key_result.IsActualError())
- return default_initial_backoff_;
- // Note: If we received a MIGRATION_DONE on download updates, then commit
- // should not have taken place. Moreover, if we receive a MIGRATION_DONE
- // on commit, it means that download updates succeeded. Therefore, we only
- // need to check if either code is equal to SERVER_RETURN_MIGRATION_DONE,
- // and not if there were any more serious errors requiring the long retry.
- if (state.last_download_updates_result.value() ==
- SyncerError::SERVER_RETURN_MIGRATION_DONE ||
- state.commit_result.value() ==
- SyncerError::SERVER_RETURN_MIGRATION_DONE) {
- return short_initial_backoff_;
- }
- // If a datatype decides the GetUpdates must be retried (e.g. because the
- // context has been updated since the request), use the short delay.
- if (state.last_download_updates_result.value() ==
- SyncerError::DATATYPE_TRIGGERED_RETRY)
- return short_initial_backoff_;
- // When the server tells us we have a conflict, then we should download the
- // latest updates so we can see the conflict ourselves, resolve it locally,
- // then try again to commit. Running another sync cycle will do all these
- // things. There's no need to back off, we can do this immediately.
- //
- // TODO(sync): We shouldn't need to handle this in BackoffDelayProvider.
- // There should be a way to deal with protocol errors before we get to this
- // point.
- if (state.commit_result.value() == SyncerError::SERVER_RETURN_CONFLICT)
- return short_initial_backoff_;
- return default_initial_backoff_;
- }
- base::TimeDelta BackoffDelayProvider::GetDelayForTesting(
- base::TimeDelta last_delay,
- int jitter_sign) {
- return GetDelayImpl(last_delay, jitter_sign);
- }
- } // namespace syncer
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