Generalize the net module's LoadLog facility from a passive container, to an event stream (NetLog).

net/url_request/request_tracker.h

-// Copyright (c) 2006-2009 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_URL_REQUEST_REQUEST_TRACKER_H_
-#define NET_URL_REQUEST_REQUEST_TRACKER_H_
-
-#include <vector>
-
-#include "base/ref_counted.h"
-#include "base/linked_list.h"
-#include "base/logging.h"
-#include "googleurl/src/gurl.h"
-#include "net/base/load_log.h"
-
-// Class to track all of the live instances of Request associated with a
-// particular URLRequestContext.  It keeps a circular queue of the LoadLogs
-// for recently deceased requests.
-template<typename Request>
-class RequestTracker {
- public:
-  struct RecentRequestInfo {
-    GURL original_url;
-    scoped_refptr<net::LoadLog> load_log;
-  };
-
-  // Helper class to make Request insertable into a base::LinkedList,
-  // without making the public interface expose base::LinkNode.
-  class Node : public base::LinkNode<Node> {
-   public:
-    Node(Request* request) : request_(request) {}
-    ~Node() {}
-
-    Request* request() const { return request_; }
-
-   private:
-    Request* request_;
-  };
-
-  typedef std::vector<RecentRequestInfo> RecentRequestInfoList;
-  typedef bool (*RecentRequestsFilterFunc)(const GURL&);
-
-  // The maximum number of entries for |graveyard_|, when in bounded mode.
-  static const size_t kMaxGraveyardSize;
-
-  // The maximum size of URLs to stuff into RecentRequestInfo, when in bounded
-  // mode.
-  static const size_t kMaxGraveyardURLSize;
-
-  // The maximum number of entries to use for LoadLogs when in bounded mode.
-  static const size_t kBoundedLoadLogMaxEntries;
-
-  RequestTracker()
-      : next_graveyard_index_(0),
-        graveyard_filter_func_(NULL),
-        is_unbounded_(false) {
-  }
-
-  ~RequestTracker() {}
-
-  // Returns a list of Requests that are alive.
-  std::vector<Request*> GetLiveRequests() {
-    std::vector<Request*> list;
-    for (base::LinkNode<Node>* node = live_instances_.head();
-         node != live_instances_.end();
-         node = node->next()) {
-      Request* request = node->value()->request();
-      list.push_back(request);
-    }
-    return list;
-  }
-
-  // Clears the circular buffer of RecentRequestInfos.
-  void ClearRecentlyDeceased() {
-    next_graveyard_index_ = 0;
-    graveyard_.clear();
-  }
-
-  // Returns a list of recently completed Requests.
-  const RecentRequestInfoList GetRecentlyDeceased() {
-    RecentRequestInfoList list;
-
-    // Copy the items from |graveyard_| (our circular queue of recently
-    // deceased request infos) into a vector, ordered from oldest to newest.
-    for (size_t i = 0; i < graveyard_.size(); ++i) {
-      size_t index = (next_graveyard_index_ + i) % graveyard_.size();
-      list.push_back(graveyard_[index]);
-    }
-    return list;
-  }
-
-  void Add(Request* request) {
-    live_instances_.Append(&request->request_tracker_node_);
-  }
-
-  void Remove(Request* request) {
-    // Remove from |live_instances_|.
-    request->request_tracker_node_.RemoveFromList();
-
-    RecentRequestInfo info;
-    request->GetInfoForTracker(&info);
-
-    if (!is_unbounded_) {
-      // Paranoia check: truncate |info.original_url| if it is really big.
-      const std::string& spec = info.original_url.possibly_invalid_spec();
-      if (spec.size() > kMaxGraveyardURLSize)
-        info.original_url = GURL(spec.substr(0, kMaxGraveyardURLSize));
-    }
-
-    if (ShouldInsertIntoGraveyard(info)) {
-      // Add into |graveyard_|.
-      InsertIntoGraveyard(info);
-    }
-  }
-
-  // This function lets you exclude requests from being saved to the graveyard.
-  // The graveyard is a circular buffer of the most recently completed
-  // requests.  Pass NULL turn off filtering. Otherwise pass in a function
-  // returns false to exclude requests, true otherwise.
-  void SetGraveyardFilter(RecentRequestsFilterFunc filter_func) {
-    graveyard_filter_func_ = filter_func;
-  }
-
-  bool IsUnbounded() const {
-    return is_unbounded_;
-  }
-
-  void SetUnbounded(bool unbounded) {
-    // No change.
-    if (is_unbounded_ == unbounded)
-      return;
-
-    // If we are going from unbounded to bounded, we need to trim the
-    // graveyard. For simplicity we will simply clear it.
-    if (is_unbounded_ && !unbounded)
-      ClearRecentlyDeceased();
-
-    is_unbounded_ = unbounded;
-  }
-
-  // Creates a LoadLog using the unbounded/bounded constraints that
-  // apply to this tracker.
-  net::LoadLog* CreateLoadLog() {
-    if (IsUnbounded())
-      return new net::LoadLog(net::LoadLog::kUnbounded);
-    return new net::LoadLog(kBoundedLoadLogMaxEntries);
-  }
-
- private:
-  bool ShouldInsertIntoGraveyard(const RecentRequestInfo& info) {
-    if (!graveyard_filter_func_)
-      return true;
-    return graveyard_filter_func_(info.original_url);
-  }
-
-  void InsertIntoGraveyard(const RecentRequestInfo& info) {
-    if (is_unbounded_) {
-      graveyard_.push_back(info);
-      return;
-    }
-
-    // Otherwise enforce a bound on the graveyard size, by treating it as a
-    // circular buffer.
-    if (graveyard_.size() < kMaxGraveyardSize) {
-      // Still growing to maximum capacity.
-      DCHECK_EQ(next_graveyard_index_, graveyard_.size());
-      graveyard_.push_back(info);
-    } else {
-      // At maximum capacity, overwite the oldest entry.
-      graveyard_[next_graveyard_index_] = info;
-    }
-    next_graveyard_index_ = (next_graveyard_index_ + 1) % kMaxGraveyardSize;
-  }
-
-  base::LinkedList<Node> live_instances_;
-
-  size_t next_graveyard_index_;
-  RecentRequestInfoList graveyard_;
-  RecentRequestsFilterFunc graveyard_filter_func_;
-  bool is_unbounded_;
-};
-
-template<typename Request>
-const size_t RequestTracker<Request>::kMaxGraveyardSize = 25;
-
-template<typename Request>
-const size_t RequestTracker<Request>::kMaxGraveyardURLSize = 1000;
-
-template<typename Request>
-const size_t RequestTracker<Request>::kBoundedLoadLogMaxEntries = 50;
-
-#endif  // NET_URL_REQUEST_REQUEST_TRACKER_H_