Remove predictor trimming mechanism in favor of MRU semantics
This patch removes a lot of logic in the predictor for a dead simple MRU.
This also updates the about:dns UI to use the recency ordering rather than
the pseudo-alphabetical algorithm it used before.
The patch adds some instrumentation around an element's index into the MRU
for UMA purposes. That instrumentation should be removed once the MRU size
is properly tuned.
This patch is a prereq for various optimizations regarding predictor
shutdown. Now, we don't need to do any trimming on shutdown, which
makes it easier to implement periodic syncing to prefs.
BUG=78451
Review-Url: https://codereview.chromium.org/2087653002
Cr-Commit-Position: refs/heads/master@{#401736}
diff --git a/chrome/browser/net/predictor.h b/chrome/browser/net/predictor.h
index a0dbec3..4d3cb59f 100644
--- a/chrome/browser/net/predictor.h
+++ b/chrome/browser/net/predictor.h
@@ -28,6 +28,7 @@
#include <string>
#include <vector>
+#include "base/containers/mru_cache.h"
#include "base/gtest_prod_util.h"
#include "base/macros.h"
#include "base/memory/weak_ptr.h"
@@ -121,6 +122,9 @@
// TODO(jar): We should do a persistent field trial to validate/optimize this.
static const int kMaxUnusedSocketLifetimeSecondsWithoutAGet;
+ // The maximum size of the MRU cache of referrers.
+ static const int kMaxReferrers;
+
// |max_concurrent| specifies how many concurrent (parallel) prefetches will
// be performed. Host lookups will be issued through |host_resolver|.
explicit Predictor(bool preconnect_enabled, bool predictor_enabled);
@@ -196,14 +200,6 @@
// domains for about:dns.
void GetHtmlInfo(std::string* output);
- // Discards any referrer for which all the suggested host names are currently
- // annotated with negligible expected-use. Scales down (diminishes) the
- // expected-use of those that remain, so that their use will go down by a
- // factor each time we trim (moving the referrer closer to being discarded in
- // a future call).
- // The task is performed synchronously and completes before returing.
- void TrimReferrersNow();
-
// Construct a ListValue object that contains all the data in the referrers_
// so that it can be persisted in a pref.
void SerializeReferrers(base::ListValue* referral_list);
@@ -238,12 +234,11 @@
// May be called from either the IO or UI thread and will PostTask
// to the IO thread if necessary.
- void SaveStateForNextStartupAndTrim();
+ void SaveStateForNextStartup();
- void SaveDnsPrefetchStateForNextStartupAndTrim(
- base::ListValue* startup_list,
- base::ListValue* referral_list,
- base::WaitableEvent* completion);
+ void SaveDnsPrefetchStateForNextStartup(base::ListValue* startup_list,
+ base::ListValue* referral_list,
+ base::WaitableEvent* completion);
// May be called from either the IO or UI thread and will PostTask
// to the IO thread if necessary.
@@ -390,30 +385,14 @@
// A map that is keyed with the host/port that we've learned were the cause
// of loading additional URLs. The list of additional targets is held
// in a Referrer instance, which is a value in this map.
- typedef std::map<GURL, Referrer> Referrers;
+ typedef base::MRUCache<GURL, Referrer> Referrers;
// Depending on the expected_subresource_use_, we may either make a TCP/IP
// preconnection, or merely pre-resolve the hostname via DNS (or even do
// nothing). The following are the threasholds for taking those actions.
static const double kPreconnectWorthyExpectedValue;
static const double kDNSPreresolutionWorthyExpectedValue;
- // Referred hosts with a subresource_use_rate_ that are less than the
- // following threshold will be discarded when we Trim() the list.
static const double kDiscardableExpectedValue;
- // During trimming operation to discard hosts for which we don't have likely
- // subresources, we multiply the expected_subresource_use_ value by the
- // following ratio until that value is less than kDiscardableExpectedValue.
- // This number should always be less than 1, an more than 0.
- static const double kReferrerTrimRatio;
-
- // Interval between periodic trimming of our whole referrer list.
- // We only do a major trimming about once an hour, and then only when the user
- // is actively browsing.
- static const int64_t kDurationBetweenTrimmingsHours;
- // Interval between incremental trimmings (to avoid inducing Jank).
- static const int64_t kDurationBetweenTrimmingIncrementsSeconds;
- // Number of referring URLs processed in an incremental trimming.
- static const size_t kUrlsTrimmedPerIncrement;
// These two members call the appropriate global functions in
// prediction_options.cc depending on which thread they are called on.
@@ -459,21 +438,6 @@
// asynchronously, provided we don't exceed concurrent resolution limit.
void StartSomeQueuedResolutions();
- // Performs trimming similar to TrimReferrersNow(), except it does it as a
- // series of short tasks by posting continuations again an again until done.
- void TrimReferrers();
-
- // Loads urls_being_trimmed_ from keys of current referrers_.
- void LoadUrlsForTrimming();
-
- // Posts a task to do additional incremental trimming of referrers_.
- void PostIncrementalTrimTask();
-
- // Calls Trim() on some or all of urls_being_trimmed_.
- // If it does not process all the URLs in that vector, it posts a task to
- // continue with them shortly (i.e., it yeilds and continues).
- void IncrementalTrimReferrers(bool trim_all_now);
-
// If we can determine immediately (i.e. synchronously) that requests to this
// URL would likely go through a proxy, then return true. Otherwise, return
// false. This is used to avoid issuing DNS requests when a fixed proxy
@@ -565,13 +529,6 @@
// orginial hostname.
Referrers referrers_;
- // List of URLs in referrers_ currently being trimmed (scaled down to
- // eventually be aged out of use).
- std::vector<GURL> urls_being_trimmed_;
-
- // A time after which we need to do more trimming of referrers.
- base::TimeTicks next_trim_time_;
-
// An observer for testing.
PredictorObserver* observer_;
