Update from https://crrev.com/311076

net/sdch/sdch_owner.cc

Index: net/sdch/sdch_owner.cc
diff --git a/net/sdch/sdch_owner.cc b/net/sdch/sdch_owner.cc
new file mode 100644
index 0000000000000000000000000000000000000000..b0e440569646d0aa8ebd30d2a9ea05297a766b9c
--- /dev/null
+++ b/net/sdch/sdch_owner.cc
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+// Copyright 2014 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 "net/sdch/sdch_owner.h"
+
+#include "base/bind.h"
+#include "base/metrics/histogram_macros.h"
+#include "base/time/default_clock.h"
+#include "net/base/sdch_manager.h"
+#include "net/base/sdch_net_log_params.h"
+
+namespace {
+
+enum DictionaryFate {
+  // A Get-Dictionary header wasn't acted on.
+  DICTIONARY_FATE_GET_IGNORED = 1,
+
+  // A fetch was attempted, but failed.
+  // TODO(rdsmith): Actually record this case.
+  DICTIONARY_FATE_FETCH_FAILED = 2,
+
+  // A successful fetch was dropped on the floor, no space.
+  DICTIONARY_FATE_FETCH_IGNORED_NO_SPACE = 3,
+
+  // A successful fetch was refused by the SdchManager.
+  DICTIONARY_FATE_FETCH_MANAGER_REFUSED = 4,
+
+  // A dictionary was successfully added.
+  DICTIONARY_FATE_ADDED = 5,
+
+  // A dictionary was evicted by an incoming dict.
+  DICTIONARY_FATE_EVICT_FOR_DICT = 6,
+
+  // A dictionary was evicted by memory pressure.
+  DICTIONARY_FATE_EVICT_FOR_MEMORY = 7,
+
+  // A dictionary was evicted on destruction.
+  DICTIONARY_FATE_EVICT_FOR_DESTRUCTION = 8,
+
+  DICTIONARY_FATE_MAX = 9
+};
+
+void RecordDictionaryFate(enum DictionaryFate fate) {
+  UMA_HISTOGRAM_ENUMERATION("Sdch3.DictionaryFate", fate, DICTIONARY_FATE_MAX);
+}
+
+void RecordDictionaryEviction(int use_count, DictionaryFate fate) {
+  DCHECK(fate == DICTIONARY_FATE_EVICT_FOR_DICT ||
+         fate == DICTIONARY_FATE_EVICT_FOR_MEMORY ||
+         fate == DICTIONARY_FATE_EVICT_FOR_DESTRUCTION);
+
+  UMA_HISTOGRAM_COUNTS_100("Sdch3.DictionaryUseCount", use_count);
+  RecordDictionaryFate(fate);
+}
+
+}  // namespace
+
+namespace net {
+
+// Adjust SDCH limits downwards for mobile.
+#if defined(OS_ANDROID) || defined(OS_IOS)
+// static
+const size_t SdchOwner::kMaxTotalDictionarySize = 1000 * 1000;
+#else
+// static
+const size_t SdchOwner::kMaxTotalDictionarySize = 20 * 1000 * 1000;
+#endif
+
+// Somewhat arbitrary, but we assume a dictionary smaller than
+// 50K isn't going to do anyone any good.  Note that this still doesn't
+// prevent download and addition unless there is less than this
+// amount of space available in storage.
+const size_t SdchOwner::kMinSpaceForDictionaryFetch = 50 * 1000;
+
+SdchOwner::SdchOwner(net::SdchManager* sdch_manager,
+                     net::URLRequestContext* context)
+    : manager_(sdch_manager),
+      fetcher_(context,
+               base::Bind(&SdchOwner::OnDictionaryFetched,
+                          // Because |fetcher_| is owned by SdchOwner, the
+                          // SdchOwner object will be available for the lifetime
+                          // of |fetcher_|.
+                          base::Unretained(this))),
+      total_dictionary_bytes_(0),
+      clock_(new base::DefaultClock),
+      max_total_dictionary_size_(kMaxTotalDictionarySize),
+      min_space_for_dictionary_fetch_(kMinSpaceForDictionaryFetch),
+      memory_pressure_listener_(
+          base::Bind(&SdchOwner::OnMemoryPressure,
+                     // Because |memory_pressure_listener_| is owned by
+                     // SdchOwner, the SdchOwner object will be available
+                     // for the lifetime of |memory_pressure_listener_|.
+                     base::Unretained(this))) {
+  manager_->AddObserver(this);
+}
+
+SdchOwner::~SdchOwner() {
+  for (auto it = local_dictionary_info_.begin();
+       it != local_dictionary_info_.end(); ++it) {
+    RecordDictionaryEviction(it->second.use_count,
+                             DICTIONARY_FATE_EVICT_FOR_DESTRUCTION);
+  }
+  manager_->RemoveObserver(this);
+}
+
+void SdchOwner::SetMaxTotalDictionarySize(size_t max_total_dictionary_size) {
+  max_total_dictionary_size_ = max_total_dictionary_size;
+}
+
+void SdchOwner::SetMinSpaceForDictionaryFetch(
+    size_t min_space_for_dictionary_fetch) {
+  min_space_for_dictionary_fetch_ = min_space_for_dictionary_fetch;
+}
+
+void SdchOwner::OnDictionaryFetched(const std::string& dictionary_text,
+                                    const GURL& dictionary_url,
+                                    const net::BoundNetLog& net_log) {
+  struct DictionaryItem {
+    base::Time last_used;
+    std::string server_hash;
+    int use_count;
+    size_t dictionary_size;
+
+    DictionaryItem() : use_count(0), dictionary_size(0) {}
+    DictionaryItem(const base::Time& last_used,
+                   const std::string& server_hash,
+                   int use_count,
+                   size_t dictionary_size)
+        : last_used(last_used),
+          server_hash(server_hash),
+          use_count(use_count),
+          dictionary_size(dictionary_size) {}
+    DictionaryItem(const DictionaryItem& rhs) = default;
+    DictionaryItem& operator=(const DictionaryItem& rhs) = default;
+    bool operator<(const DictionaryItem& rhs) const {
+      return last_used < rhs.last_used;
+    }
+  };
+
+  std::vector<DictionaryItem> stale_dictionary_list;
+  size_t recoverable_bytes = 0;
+  base::Time stale_boundary(clock_->Now() - base::TimeDelta::FromDays(1));
+  for (auto used_it = local_dictionary_info_.begin();
+       used_it != local_dictionary_info_.end(); ++used_it) {
+    if (used_it->second.last_used < stale_boundary) {
+      stale_dictionary_list.push_back(
+          DictionaryItem(used_it->second.last_used, used_it->first,
+                         used_it->second.use_count, used_it->second.size));
+      recoverable_bytes += used_it->second.size;
+    }
+  }
+
+  if (total_dictionary_bytes_ + dictionary_text.size() - recoverable_bytes >
+      max_total_dictionary_size_) {
+    RecordDictionaryFate(DICTIONARY_FATE_FETCH_IGNORED_NO_SPACE);
+    net::SdchManager::SdchErrorRecovery(SDCH_DICTIONARY_NO_ROOM);
+    net_log.AddEvent(net::NetLog::TYPE_SDCH_DICTIONARY_ERROR,
+                     base::Bind(&net::NetLogSdchDictionaryFetchProblemCallback,
+                                SDCH_DICTIONARY_NO_ROOM, dictionary_url, true));
+    return;
+  }
+
+  // Evict from oldest to youngest until we have space.
+  std::sort(stale_dictionary_list.begin(), stale_dictionary_list.end());
+  size_t avail_bytes = max_total_dictionary_size_ - total_dictionary_bytes_;
+  auto stale_it = stale_dictionary_list.begin();
+  while (avail_bytes < dictionary_text.size() &&
+         stale_it != stale_dictionary_list.end()) {
+    manager_->RemoveSdchDictionary(stale_it->server_hash);
+    RecordDictionaryEviction(stale_it->use_count,
+                             DICTIONARY_FATE_EVICT_FOR_DICT);
+    local_dictionary_info_.erase(stale_it->server_hash);
+    avail_bytes += stale_it->dictionary_size;
+    ++stale_it;
+  }
+  DCHECK(avail_bytes >= dictionary_text.size());
+
+  std::string server_hash;
+  net::SdchProblemCode rv = manager_->AddSdchDictionary(
+      dictionary_text, dictionary_url, &server_hash);
+  if (rv != net::SDCH_OK) {
+    RecordDictionaryFate(DICTIONARY_FATE_FETCH_MANAGER_REFUSED);
+    net::SdchManager::SdchErrorRecovery(rv);
+    net_log.AddEvent(net::NetLog::TYPE_SDCH_DICTIONARY_ERROR,
+                     base::Bind(&net::NetLogSdchDictionaryFetchProblemCallback,
+                                rv, dictionary_url, true));
+    return;
+  }
+
+  RecordDictionaryFate(DICTIONARY_FATE_ADDED);
+
+  DCHECK(local_dictionary_info_.end() ==
+         local_dictionary_info_.find(server_hash));
+  total_dictionary_bytes_ += dictionary_text.size();
+  local_dictionary_info_[server_hash] = DictionaryInfo(
+      // Set the time last used to something to avoid thrashing, but not recent,
+      // to avoid taking too much time/space with useless dictionaries/one-off
+      // visits to web sites.
+      clock_->Now() - base::TimeDelta::FromHours(23), dictionary_text.size());
+}
+
+void SdchOwner::OnDictionaryUsed(SdchManager* manager,
+                                 const std::string& server_hash) {
+  auto it = local_dictionary_info_.find(server_hash);
+  DCHECK(local_dictionary_info_.end() != it);
+
+  it->second.last_used = clock_->Now();
+  it->second.use_count++;
+}
+
+void SdchOwner::OnGetDictionary(net::SdchManager* manager,
+                                const GURL& request_url,
+                                const GURL& dictionary_url) {
+  base::Time stale_boundary(clock_->Now() - base::TimeDelta::FromDays(1));
+  size_t avail_bytes = 0;
+  for (auto it = local_dictionary_info_.begin();
+       it != local_dictionary_info_.end(); ++it) {
+    if (it->second.last_used < stale_boundary)
+      avail_bytes += it->second.size;
+  }
+
+  // Don't initiate the fetch if we wouldn't be able to store any
+  // reasonable dictionary.
+  // TODO(rdsmith): Maybe do a HEAD request to figure out how much
+  // storage we'd actually need?
+  if (max_total_dictionary_size_ < (total_dictionary_bytes_ - avail_bytes +
+                                    min_space_for_dictionary_fetch_)) {
+    RecordDictionaryFate(DICTIONARY_FATE_GET_IGNORED);
+    // TODO(rdsmith): Log a net-internals error.  This requires
+    // SdchManager to forward the URLRequest that detected the
+    // Get-Dictionary header to its observers, which is tricky
+    // because SdchManager is layered underneath URLRequest.
+    return;
+  }
+
+  fetcher_.Schedule(dictionary_url);
+}
+
+void SdchOwner::OnClearDictionaries(net::SdchManager* manager) {
+  total_dictionary_bytes_ = 0;
+  local_dictionary_info_.clear();
+  fetcher_.Cancel();
+}
+
+void SdchOwner::SetClockForTesting(scoped_ptr<base::Clock> clock) {
+  clock_ = clock.Pass();
+}
+
+void SdchOwner::OnMemoryPressure(
+    base::MemoryPressureListener::MemoryPressureLevel level) {
+  DCHECK_NE(base::MemoryPressureListener::MEMORY_PRESSURE_LEVEL_NONE, level);
+
+  for (auto it = local_dictionary_info_.begin();
+       it != local_dictionary_info_.end(); ++it) {
+    RecordDictionaryEviction(it->second.use_count,
+                             DICTIONARY_FATE_EVICT_FOR_MEMORY);
+  }
+
+  // TODO(rdsmith): Make a distinction between moderate and critical
+  // memory pressure.
+  manager_->ClearData();
+}
+
+}  // namespace net