Move part of metrics from chrome/common to components

chrome/common/metrics/metrics_log_manager.h

-// 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.
-
-#ifndef CHROME_COMMON_METRICS_METRICS_LOG_MANAGER_H_
-#define CHROME_COMMON_METRICS_METRICS_LOG_MANAGER_H_
-
-
-#include <string>
-#include <vector>
-
-#include "base/basictypes.h"
-#include "base/memory/scoped_ptr.h"
-#include "chrome/common/metrics/metrics_log_base.h"
-
-// Manages all the log objects used by a MetricsService implementation. Keeps
-// track of both an in progress log and a log that is staged for uploading as
-// text, as well as saving logs to, and loading logs from, persistent storage.
-class MetricsLogManager {
- public:
-  typedef MetricsLogBase::LogType LogType;
-
-  MetricsLogManager();
-  ~MetricsLogManager();
-
-  class SerializedLog {
-   public:
-    SerializedLog();
-    ~SerializedLog();
-
-    const std::string& log_text() const { return log_text_; }
-    const std::string& log_hash() const { return log_hash_; }
-
-    // Returns true if the log is empty.
-    bool IsEmpty() const;
-
-    // Swaps log text with |log_text| and updates the hash. This is more
-    // performant than a regular setter as it avoids doing a large string copy.
-    void SwapLogText(std::string* log_text);
-
-    // Clears the log.
-    void Clear();
-
-    // Swaps log contents with |other|.
-    void Swap(SerializedLog* other);
-
-   private:
-    // Non-human readable log text (serialized proto).
-    std::string log_text_;
-
-    // Non-human readable SHA1 of |log_text| or empty if |log_text| is empty.
-    std::string log_hash_;
-
-    // Intentionally omits DISALLOW_COPY_AND_ASSIGN() so that it can be used
-    // in std::vector<SerializedLog>.
-  };
-
-  enum StoreType {
-    NORMAL_STORE,       // A standard store operation.
-    PROVISIONAL_STORE,  // A store operation that can be easily reverted later.
-  };
-
-  // Takes ownership of |log| and makes it the current_log. This should only be
-  // called if there is not a current log.
-  void BeginLoggingWithLog(MetricsLogBase* log);
-
-  // Returns the in-progress log.
-  MetricsLogBase* current_log() { return current_log_.get(); }
-
-  // Closes current_log(), compresses it, and stores the compressed log for
-  // later, leaving current_log() NULL.
-  void FinishCurrentLog();
-
-  // Returns true if there are any logs waiting to be uploaded.
-  bool has_unsent_logs() const {
-    return !unsent_initial_logs_.empty() || !unsent_ongoing_logs_.empty();
-  }
-
-  // Populates staged_log_text() with the next stored log to send.
-  // Should only be called if has_unsent_logs() is true.
-  void StageNextLogForUpload();
-
-  // Returns true if there is a log that needs to be, or is being, uploaded.
-  bool has_staged_log() const;
-
-  // The text of the staged log, as a serialized protobuf. Empty if there is no
-  // staged log, or if compression of the staged log failed.
-  const std::string& staged_log_text() const { return staged_log_.log_text(); }
-
-  // The SHA1 hash (non-human readable) of the staged log or empty if there is
-  // no staged log.
-  const std::string& staged_log_hash() const { return staged_log_.log_hash(); }
-
-  // Discards the staged log.
-  void DiscardStagedLog();
-
-  // Closes and discards |current_log|.
-  void DiscardCurrentLog();
-
-  // Sets current_log to NULL, but saves the current log for future use with
-  // ResumePausedLog(). Only one log may be paused at a time.
-  // TODO(stuartmorgan): Pause/resume support is really a workaround for a
-  // design issue in initial log writing; that should be fixed, and pause/resume
-  // removed.
-  void PauseCurrentLog();
-
-  // Restores the previously paused log (if any) to current_log().
-  // This should only be called if there is not a current log.
-  void ResumePausedLog();
-
-  // Saves the staged log, then clears staged_log().
-  // If |store_type| is PROVISIONAL_STORE, it can be dropped from storage with
-  // a later call to DiscardLastProvisionalStore (if it hasn't already been
-  // staged again).
-  // This is intended to be used when logs are being saved while an upload is in
-  // progress, in case the upload later succeeds.
-  // This can only be called if has_staged_log() is true.
-  void StoreStagedLogAsUnsent(StoreType store_type);
-
-  // Discards the last log stored with StoreStagedLogAsUnsent with |store_type|
-  // set to PROVISIONAL_STORE, as long as it hasn't already been re-staged. If
-  // the log is no longer present, this is a no-op.
-  void DiscardLastProvisionalStore();
-
-  // Sets the threshold for how large an onging log can be and still be written
-  // to persistant storage. Ongoing logs larger than this will be discarded
-  // before persisting. 0 is interpreted as no limit.
-  void set_max_ongoing_log_store_size(size_t max_size) {
-    max_ongoing_log_store_size_ = max_size;
-  }
-
-  // Interface for a utility class to serialize and deserialize logs for
-  // persistent storage.
-  class LogSerializer {
-   public:
-    virtual ~LogSerializer() {}
-
-    // Serializes |logs| to persistent storage, replacing any previously
-    // serialized logs of the same type.
-    virtual void SerializeLogs(const std::vector<SerializedLog>& logs,
-                               LogType log_type) = 0;
-
-    // Populates |logs| with logs of type |log_type| deserialized from
-    // persistent storage.
-    virtual void DeserializeLogs(LogType log_type,
-                                 std::vector<SerializedLog>* logs) = 0;
-  };
-
-  // Sets the serializer to use for persisting and loading logs; takes ownership
-  // of |serializer|.
-  void set_log_serializer(LogSerializer* serializer) {
-    log_serializer_.reset(serializer);
-  }
-
-  // Saves any unsent logs to persistent storage using the current log
-  // serializer. Can only be called after set_log_serializer.
-  void PersistUnsentLogs();
-
-  // Loads any unsent logs from persistent storage using the current log
-  // serializer. Can only be called after set_log_serializer.
-  void LoadPersistedUnsentLogs();
-
- private:
-  // Saves |log| as the given type (or discards it in accordance with
-  // |max_ongoing_log_store_size_|).
-  // NOTE: This clears the contents of |log| (to avoid an expensive copy),
-  // so the log should be discarded after this call.
-  void StoreLog(SerializedLog* log,
-                LogType log_type,
-                StoreType store_type);
-
-  // Compresses |current_log_| into |compressed_log|.
-  void CompressCurrentLog(SerializedLog* compressed_log);
-
-  // Tracks whether unsent logs (if any) have been loaded from the serializer.
-  bool unsent_logs_loaded_;
-
-  // The log that we are still appending to.
-  scoped_ptr<MetricsLogBase> current_log_;
-
-  // A paused, previously-current log.
-  scoped_ptr<MetricsLogBase> paused_log_;
-
-  // Helper class to handle serialization/deserialization of logs for persistent
-  // storage. May be NULL.
-  scoped_ptr<LogSerializer> log_serializer_;
-
-  // The current staged log, ready for upload to the server.
-  SerializedLog staged_log_;
-  LogType staged_log_type_;
-
-  // Logs from a previous session that have not yet been sent.
-  // Note that the vector has the oldest logs listed first (early in the
-  // vector), and we'll discard old logs if we have gathered too many logs.
-  std::vector<SerializedLog> unsent_initial_logs_;
-  std::vector<SerializedLog> unsent_ongoing_logs_;
-
-  size_t max_ongoing_log_store_size_;
-
-  // The index and type of the last provisional store. If nothing has been
-  // provisionally stored, or the last provisional store has already been
-  // re-staged, the index will be -1;
-  // This is necessary because during an upload there are two logs (staged
-  // and current) and a client might store them in either order, so it's
-  // not necessarily the case that the provisional store is the last store.
-  int last_provisional_store_index_;
-  LogType last_provisional_store_type_;
-
-  DISALLOW_COPY_AND_ASSIGN(MetricsLogManager);
-};
-
-#endif  // CHROME_COMMON_METRICS_METRICS_LOG_MANAGER_H_