// Copyright (C) 2016 The Android Open Source Project
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package com.google.gerrit.server.notedb;

import com.google.gerrit.metrics.Counter1;
import com.google.gerrit.metrics.Description;
import com.google.gerrit.metrics.Description.Units;
import com.google.gerrit.metrics.Field;
import com.google.gerrit.metrics.MetricMaker;
import com.google.gerrit.metrics.Timer1;
import com.google.inject.Inject;
import com.google.inject.Singleton;

@Singleton
class NoteDbMetrics {
  /** End-to-end latency for writing a collection of updates. */
  final Timer1<NoteDbTable> updateLatency;

  /**
   * The portion of {@link #updateLatency} due to preparing the sequence of
   * updates.
   * <p>
   * May include some I/O (e.g. reading old refs), but excludes writes.
   */
  final Timer1<NoteDbTable> stageUpdateLatency;

  /**
   * End-to-end latency for reading changes from NoteDb, including reading
   * ref(s) and parsing.
   */
  final Timer1<NoteDbTable> readLatency;

  /**
   * The portion of {@link #readLatency} due to parsing commits, but excluding
   * I/O (to a best effort).
   */
  final Timer1<NoteDbTable> parseLatency;

  /**
   * Latency due to auto-rebuilding entities when out of date.
   * <p>
   * Excludes latency from reading ref to check whether the entity is up to
   * date.
   */
  final Timer1<NoteDbTable> autoRebuildLatency;

  /** Count of auto-rebuild attempts that failed. */
  final Counter1<NoteDbTable> autoRebuildFailureCount;

  @Inject
  NoteDbMetrics(MetricMaker metrics) {
    Field<NoteDbTable> view = Field.ofEnum(NoteDbTable.class, "table");

    updateLatency = metrics.newTimer(
        "notedb/update_latency",
        new Description("NoteDb update latency by table")
            .setCumulative()
            .setUnit(Units.MILLISECONDS),
        view);

    stageUpdateLatency = metrics.newTimer(
        "notedb/stage_update_latency",
        new Description("Latency for staging updates to NoteDb by table")
            .setCumulative()
            .setUnit(Units.MICROSECONDS),
        view);

    readLatency = metrics.newTimer(
        "notedb/read_latency",
        new Description("NoteDb read latency by table")
            .setCumulative()
            .setUnit(Units.MILLISECONDS),
        view);

    parseLatency = metrics.newTimer(
        "notedb/parse_latency",
        new Description("NoteDb parse latency by table")
            .setCumulative()
            .setUnit(Units.MICROSECONDS),
        view);

    autoRebuildLatency = metrics.newTimer(
        "notedb/auto_rebuild_latency",
        new Description("NoteDb auto-rebuilding latency by table")
            .setCumulative()
            .setUnit(Units.MILLISECONDS),
        view);

    autoRebuildFailureCount = metrics.newCounter(
        "notedb/auto_rebuild_failure_count",
        new Description("NoteDb auto-rebuilding attempts that failed by table")
            .setCumulative(),
        view);
  }
}