tools/metrics/histograms/histograms_xml/ukm/histograms.xml

<!--
Copyright 2020 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.
-->

<!--
This file is used to generate a comprehensive list of UKM histograms
along with a detailed description for each histogram.

For best practices on writing histogram descriptions, see
https://chromium.googlesource.com/chromium/src.git/+/HEAD/tools/metrics/histograms/README.md

Please send CLs to chromium-metrics-reviews@google.com rather than to specific
individuals. These CLs will be automatically reassigned to a reviewer within
about 5 minutes. This approach helps the metrics team to load-balance incoming
reviews. Googlers can read more about this at go/gwsq-gerrit.
-->

<histogram-configuration>

<histograms>

<histogram name="UKM.ActualLogUploadInterval" units="minutes"
    expires_after="2021-07-01">
  <owner>rkaplow@chromium.org</owner>
  <owner>ukm-team@google.com</owner>
  <summary>
    The actual interval between log upload start and previous log upload
    finished within the same process. A value of 0 indicates there was no
    previous upload.
  </summary>
</histogram>

<histogram name="UKM.BuildAndStoreLogIsEmpty" enum="Boolean"
    expires_after="2021-07-01">
  <owner>rkaplow@chromium.org</owner>
  <owner>ukm-team@google.com</owner>
  <summary>
    Emitted when UKM Service attempts to build and store a log. Emits true if it
    was empty (no sources or entries) which means no log is written, false
    otherwise.
  </summary>
</histogram>

<histogram name="UKM.ConsentObserver.AllowedForAllProfiles" enum="Boolean"
    expires_after="2020-08-30">
  <owner>bcwhite@chromium.org</owner>
  <owner>rkaplow@chromium.org</owner>
  <owner>ukm-team@google.com</owner>
  <summary>
    Logged in UpdateUkmAllowedForAllProfiles from the UkmConsentStateObserver
    which is called when UkmConsentStateObserver starts observing a new profile
    and every time a URL-keyed anonymized data collection state changes or a
    sync service state changes. This records whether UKM is allowed for all
    profiles.
  </summary>
</histogram>

<histogram name="UKM.ConsentObserver.Purge" enum="Boolean"
    expires_after="2021-07-01">
  <owner>bcwhite@chromium.org</owner>
  <owner>rkaplow@chromium.org</owner>
  <owner>ukm-team@google.com</owner>
  <summary>
    Logged in the UpdateProfileState call from the UkmConsentStateObserver. This
    records if the UKM allowed change will trigger a purge of the local UKM
    data.
  </summary>
</histogram>

<histogram name="UKM.Entries.Dropped" enum="UkmDataDroppedReason"
    expires_after="2021-06-13">
  <owner>rkaplow@chromium.org</owner>
  <owner>ukm-team@google.com</owner>
  <summary>
    Number of UKM entries that are dropped. Categorized by the cause of it being
    dropped.
  </summary>
</histogram>

<histogram name="UKM.Entries.Dropped.ByEntryHash" enum="UkmEventNameHash"
    expires_after="2021-07-04">
  <owner>jwd@chromium.org</owner>
  <owner>ukm-team@google.com</owner>
  <summary>
    The hashed name of the UKM entry being dropped. The hash is the same hash
    sent in the UKM log but truncated to 31 bits with &quot;event_hash &amp;
    0x7fffffff&quot;. Recorded when adding an entry and the UKM recorder decides
    it should be dropped.
  </summary>
</histogram>

<histogram name="UKM.Entries.Recorded.ByEntryHash" enum="UkmEventNameHash"
    expires_after="2021-07-04">
  <owner>yrsun@chromium.org</owner>
  <owner>ukm-team@google.com</owner>
  <summary>
    The hashed name of the UKM entry being recorded. The hash is the same hash
    sent in the UKM log but truncated to 31 bits with &quot;event_hash &amp;
    0x7fffffff&quot;. Recorded when an entry is added and accepted by the UKM
    recorder.
  </summary>
</histogram>

<histogram name="UKM.Entries.SerializedCount2" units="entries"
    expires_after="2021-06-13">
  <owner>rkaplow@chromium.org</owner>
  <owner>ukm-team@google.com</owner>
  <summary>Number of serialized UKM entries when storing a UKM log.</summary>
</histogram>

<histogram name="UKM.Entries.SerializedCountFCP" units="entries"
    expires_after="2021-07-01">
  <owner>rkaplow@chromium.org</owner>
  <owner>ukm-team@google.com</owner>
  <summary>
    Number of serialized UKM entries that are of type PageLoad that have the
    metric PaintTiming.NavigationToFirstContentfulPaint. This is recorded every
    time a UKM log is stored.
  </summary>
</histogram>

<histogram name="UKM.InitSequence" enum="UmaInitSequence"
    expires_after="2021-07-01">
  <owner>rkaplow@chromium.org</owner>
  <owner>ukm-team@google.com</owner>
  <summary>
    Logged during UkmService initialization whether the init task or the initial
    log timer completed first. The expectation is the vast majority of the time,
    the init task should complete first. If metrics show otherwise, then it may
    indicate there's a bug in the UkmService init sequence and that it should be
    investigated.
  </summary>
</histogram>

<histogram name="UKM.IOSLog.OnSuccess" units="records"
    expires_after="2021-07-11">
  <owner>eugenebut@chromium.org</owner>
  <owner>rkaplow@chromium.org</owner>
  <summary>
    Number of times when UKM.LogSize.OnSuccess was recorded on iOS. Recorded
    when the app transitions to the foreground. This histogram should help to
    figure out the root cause of crbug.com/1154678 (Data loss on UMA in iOS). If
    total count of UKM.IOSLog.OnSuccess is greater than number of
    UKM.LogSize.OnSuccess records, then data loss is caused by failure to write
    the histogram to the disk on background thread. Otherwise (if total sum of
    UKM.IOSLog.OnSuccess is equal to total count of UKM.LogSize.OnSuccess
    records) then there is actually no data loss and app simply gets terminated
    in a short window between UKM reached the server and the API call which
    records the data.
  </summary>
</histogram>

<histogram name="UKM.LogSize.OnSuccess" units="KB" expires_after="2021-06-13">
  <owner>rkaplow@chromium.org</owner>
  <owner>ukm-team@google.com</owner>
  <summary>
    Size in kilobytes (after compression) of an uploaded UKM log. Recorded after
    a successful UKM upload.

    Note: A related metric (UKM.ProtoCompressionRatio) logs the compression
    ratio.
  </summary>
</histogram>

<histogram name="UKM.LogUpload.Canceled.CellularConstraint"
    enum="BooleanCanceled" expires_after="2021-07-01">
  <owner>rkaplow@chromium.org</owner>
  <owner>ukm-team@google.com</owner>
  <summary>
    Logs whether a log was not uploaded due to cellular log throttling logic.
    Android only.
  </summary>
</histogram>

<histogram name="UKM.LogUpload.ResponseOrErrorCode"
    enum="CombinedHttpResponseAndNetErrorCode" expires_after="2021-06-20">
  <owner>rkaplow@chromium.org</owner>
  <owner>ukm-team@google.com</owner>
  <summary>
    HTTP response codes and network errors encountered by UKM when attempting to
    upload logs to the server.
  </summary>
</histogram>

<histogram name="UKM.MigratedClientIdInt64ToUInt64" enum="BooleanMigrated"
    expires_after="2021-07-01">
  <owner>jwd@chromium.org</owner>
  <owner>rkaplow@chromium.org</owner>
  <owner>ukm-team@google.com</owner>
  <summary>
    The client id was migrated from an Int64 pref to a UInt64 pref. Not migrated
    is recorded when a valid UInt64 value is loaded from prefs. Migration
    started in M75.
  </summary>
</histogram>

<histogram name="UKM.PersistentLogRecall.Status"
    enum="PersistedLogsLogReadStatus" expires_after="2021-07-01">
  <owner>rkaplow@chromium.org</owner>
  <owner>ukm-team@google.com</owner>
  <summary>The status when loading UKM PersistedLogs from Prefs.</summary>
</histogram>

<histogram name="UKM.ProtoCompressionRatio" units="%"
    expires_after="2021-02-07">
  <owner>rkaplow@chromium.org</owner>
  <owner>src/base/metrics/OWNERS</owner>
  <summary>
    Compression ratio of the serialized protobuf that will be uploaded to the
    UKM server. This serialized protobuf is compressed using gzip. See also
    UKM.LogSize.OnSuccess.
  </summary>
</histogram>

<histogram name="UKM.ReportSize.NonUkmPercentage" units="%"
    expires_after="2021-07-01">
  <owner>yrsun@chromium.org</owner>
  <owner>ukm-team@google.com</owner>
  <summary>
    Percentage that data non-directly attributed (e.g. system profile info, etc)
    to UKM take up in a serialized ukm::Report protocol buffer, before
    compression.
  </summary>
</histogram>

<histogram name="UKM.ResetReason" enum="UkmResetReason"
    expires_after="2021-07-01">
  <owner>rkaplow@chromium.org</owner>
  <owner>ukm-team@google.com</owner>
  <summary>
    Recorded when a UKM client state (client_id, session_id) is reset. This
    emits the reason the resetting was triggered.
  </summary>
</histogram>

<histogram name="UKM.Sources.Dropped" enum="UkmDataDroppedReason"
    expires_after="2021-06-13">
  <owner>rkaplow@chromium.org</owner>
  <owner>ukm-team@google.com</owner>
  <summary>
    Number of UKM sources that are dropped. Categorized by the cause of it being
    dropped.
  </summary>
</histogram>

<histogram name="UKM.Sources.KeptSourcesCount" units="sources"
    expires_after="2021-06-13">
  <owner>rkaplow@chromium.org</owner>
  <owner>ukm-team@google.com</owner>
  <summary>
    Number of unsent UKM sources that were kept in-memory to be potentially
    transmitted in the next log.
  </summary>
</histogram>

<histogram name="UKM.Sources.SerializedCount2{UkmSourceIdTypes}"
    units="sources" expires_after="2021-02-14">
  <owner>rkaplow@chromium.org</owner>
  <owner>ukm-team@google.com</owner>
  <summary>
    Number of serialized UKM sources when storing a UKM log. {UkmSourceIdTypes}
  </summary>
  <token key="UkmSourceIdTypes">
    <variant name=""/>
    <variant name=".App" summary="Restricted to app source id types."/>
    <variant name=".Default" summary="Restricted to default source id type."/>
    <variant name=".Navigation"
        summary="Restricted to navigation source id types."/>
    <variant name=".Ukm"
        summary="Restricted to UKM source id types. Deprecated and replaced
                 by 'Default' in 2020/05."/>
  </token>
</histogram>

<histogram name="UKM.Sources.UnmatchedSourcesCount" units="sources"
    expires_after="2021-07-01">
  <owner>rkaplow@chromium.org</owner>
  <owner>ukm-team@google.com</owner>
  <summary>
    Number of UKM sources that were not sent because they did not match a
    navigation source URL.
  </summary>
</histogram>

<histogram name="UKM.Sources.UnsentSourcesCount" units="sources"
    expires_after="2021-06-13">
  <owner>rkaplow@chromium.org</owner>
  <owner>ukm-team@google.com</owner>
  <summary>
    Number of UKM sources that were not sent because they had no associated
    entries.
  </summary>
</histogram>

<histogram name="UKM.UnsentLogs.DroppedSize" units="bytes"
    expires_after="2021-06-27">
  <owner>rkaplow@chromium.org</owner>
  <owner>ukm-team@google.com</owner>
  <summary>
    Number of bytes in an excessively large log that was discarded while
    persisting UKM logs to disk to retry during next chrome run.
  </summary>
</histogram>

<histogram name="UKM.UnsentLogs.NumDropped" units="units"
    expires_after="2021-06-13">
  <owner>rkaplow@chromium.org</owner>
  <owner>ukm-team@google.com</owner>
  <summary>
    Counter for number of UKM unsent logs removed from persistent storage.
  </summary>
</histogram>

<histogram name="UKM.UserDemographics.Status" enum="UserDemographicsStatus"
    expires_after="2020-07-01">
  <owner>vincb@google.com</owner>
  <owner>ukm-team@google.com</owner>
  <summary>
    The status of the retrieval of user demographics from sync that are reported
    to UKM. Emitted each time UKM metrics are reported.
  </summary>
</histogram>

</histograms>

</histogram-configuration>