<!--
Copyright 2021 The Chromium Authors
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 Prefetch 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 follow the instructions in the OWNERS file in this directory to find a
reviewer. If no OWNERS file exists, please consider signing up at
go/reviewing-metrics (Googlers only), as all subdirectories are expected to
have an OWNERS file. As a last resort you can send the CL to
[email protected].
-->
<histogram-configuration>
<histograms>
<variants name="PrefetchProxyCanaryCheckerClient">
<variant name="DNS" summary="DNS canary check"/>
<variant name="TLS" summary="TLS canary check"/>
</variants>
<variants name="SpeculationEagerness">
<variant name="Conservative" summary="Conservative"/>
<variant name="Eager" summary="Eager"/>
<variant name="Moderate" summary="Moderate"/>
</variants>
<histogram
name="PrefetchProxy.AfterClick.BlockUntilHeadDuration.{WasServed}.{SpeculationEagerness}"
units="ms" expires_after="2025-01-05">
<owner>[email protected]</owner>
<owner>[email protected]</owner>
<summary>
If a prefetch request has started but the head of the prefetch response has
not been received yet when a navigation to a URL that matches the prefetch,
then the prefetch service will block until the head of the prefetch response
is received and then decide to serve or not serve the prefetch.
This histogram records the amount of time that the prefetch service blocked
until the head of the prefetch response was received. This histogram is only
recorded for prefetches that are {WasServed} and with an Eagerness of
{SpeculationEagerness}.
</summary>
<token key="WasServed">
<variant name="NotServed" summary="not served"/>
<variant name="Served" summary="served"/>
</token>
<token key="SpeculationEagerness" variants="SpeculationEagerness"/>
</histogram>
<histogram
name="PrefetchProxy.AfterClick.Mainframe.CookieCopyStartToInterceptorCheck"
units="ms" expires_after="2024-09-01">
<owner>[email protected]</owner>
<owner>[email protected]</owner>
<summary>
Cross-Origin prefetches requested via the Speculation Rules API are made in
an isolated network context. When the prefetched link is navigated to, the
cookies are copied from this isolated network context to the user's default
network context.
This histogram records the time from the start of the cookie copy to when
the URL interceptor trying to serve the prefetch checks the status of the
cookie copy.
</summary>
</histogram>
<histogram name="PrefetchProxy.AfterClick.Mainframe.CookieCopyTime" units="ms"
expires_after="2025-01-05">
<owner>[email protected]</owner>
<owner>[email protected]</owner>
<summary>
Cross-Origin prefetches requested via the Speculation Rules API are made in
an isolated network context. When the prefetched link is navigated to, the
cookies are copied from this isolated network context to the user's default
network context.
This histogram records the time required to copy cookies from the isolated
network context used for a prefetch to the user's default network context
after a prefetched link is navigated to.
</summary>
</histogram>
<histogram name="PrefetchProxy.AfterClick.Mainframe.CookieReadTime" units="ms"
expires_after="2024-09-22">
<owner>[email protected]</owner>
<owner>[email protected]</owner>
<summary>
Cross-Origin prefetches requested via the Speculation Rules API are made in
an isolated network context. When the prefetched link is na vigated to, the
cookies are copied from this isolated network context to the user's default
network context.
This histogram records the time required to read the cookies from the
isolated network context used for a prefetch before being copied to the
user's default network context after a prefetched link is navigated to. Note
this does not include the time it takes to write the cookies to the default
network context.
</summary>
</histogram>
<histogram name="PrefetchProxy.AfterClick.Mainframe.CookieWaitTime" units="ms"
expires_after="2024-09-01">
<owner>[email protected]</owner>
<owner>[email protected]</owner>
<summary>
Records the amount of time that the navigation to a previously prefetched
page was delayed because cookies had to be copied from the isolated cookie
jar.
This is only the amount of time in which the cookie copy process blocks
intercepting the navigation. The overall time it takes for the cookie copy
process is recorded to the
"PrefetchProxy.AfterClick.Mainframe.Cookie(Copy|Read|Write)Time"
histograms.
</summary>
</histogram>
<histogram name="PrefetchProxy.AfterClick.Mainframe.CookieWriteTime" units="ms"
expires_after="2024-09-01">
<owner>[email protected]</owner>
<owner>[email protected]</owner>
<summary>
Cross-Origin prefetches requested via the Speculation Rules API are made in
an isolated network context. When the prefetched link is na vigated to, the
cookies are copied from this isolated network context to the user's default
network context.
This histogram records the time required to write cookies from the isolated
network context used for a prefetch to the user's default network context
after a prefetched link is navigated to. Note this does not include the time
it takes to read the cookies from the isolated network context.
</summary>
</histogram>
<histogram name="PrefetchProxy.AfterClick.RedirectChainSize" units="count"
expires_after="2024-09-01">
<owner>[email protected]</owner>
<owner>[email protected]</owner>
<summary>
The redirect chain size of a served prefetch. This histogram is recorded
only for prefetches that are served for a navigation.
</summary>
</histogram>
<histogram
name="PrefetchProxy.AfterClick.WasBlockedUntilHeadWhenServing.{SpeculationEagerness}"
enum="Boolean" expires_after="2025-01-05">
<owner>[email protected]</owner>
<owner>[email protected]</owner>
<summary>
If a prefetch request has started but the head of the prefetch response has
not been received yet when a navigation to a URL that matches the prefetch,
then the prefetch service will block until the head of the prefetch response
is received and then decide to serve or not serve the prefetch.
This histogram records whether or not prefetch service will block or not for
a prefetch. This histogram is only for prefetches with an Eagerness of
{SpeculationEagerness}.
</summary>
<token key="SpeculationEagerness" variants="SpeculationEagerness"/>
</histogram>
<histogram name="PrefetchProxy.AfterClick.WasFullRedirectChainServed"
enum="Boolean" expires_after="2025-01-05">
<owner>[email protected]</owner>
<owner>[email protected]</owner>
<summary>
Whether the full redirect chain of a prefetch is served (true), or just part
of the redirect was served (false). This histogram is only recorded when: 1)
the prefetch had at least one redirect (i.e. the redirect chain is at least
2), and 2) at least part of prefetch redirect chain is served.
</summary>
</histogram>
<histogram
name="PrefetchProxy.CanaryChecker.CacheEntryAge.{PrefetchProxyCanaryCheckerClient}"
units="hours" expires_after="2025-02-23">
<owner>[email protected]</owner>
<owner>[email protected]</owner>
<summary>
How old a cached probe result was when it was used, in hours.
</summary>
<token key="PrefetchProxyCanaryCheckerClient"
variants="PrefetchProxyCanaryCheckerClient"/>
</histogram>
<histogram
name="PrefetchProxy.CanaryChecker.CacheLookupResult.{PrefetchProxyCanaryCheckerClient}"
enum="CanaryCheckLookupResult" expires_after="2024-09-01">
<owner>[email protected]</owner>
<owner>[email protected]</owner>
<summary>
Records the status of canary check cache lookups. A sample is recorded every
time Chrome attempts to use a resource prefetched using the prefetch proxy.
Cache misses or cached failures result in filter probing the origin before
the prefetched response can be used.
</summary>
<token key="PrefetchProxyCanaryCheckerClient"
variants="PrefetchProxyCanaryCheckerClient"/>
</histogram>
<histogram
name="PrefetchProxy.CanaryChecker.FinalState.{PrefetchProxyCanaryCheckerClient}"
enum="BooleanSuccess" expires_after="2024-09-01">
<owner>[email protected]</owner>
<owner>[email protected]</owner>
<summary>
Records the end state of a probe just before it goes inactive. This happens
when the prober succeeds, fails and has no more retries, or the delegate
stops probing.
</summary>
<token key="PrefetchProxyCanaryCheckerClient"
variants="PrefetchProxyCanaryCheckerClient"/>
</histogram>
<histogram
name="PrefetchProxy.CanaryChecker.GenerateCacheKey.{PrefetchProxyCanaryCheckerClient}"
units="ms" expires_after="2024-09-01">
<owner>[email protected]</owner>
<owner>[email protected]</owner>
<summary>
Records the amount of time spent generating a cache key for the availability
prober. In particular, this tracks how much getNetworkOperator calls might
be slowing down this method. See crbug.com/1266018 for more details.
</summary>
<token key="PrefetchProxyCanaryCheckerClient"
variants="PrefetchProxyCanaryCheckerClient"/>
</histogram>
<histogram
name="PrefetchProxy.CanaryChecker.NetError.{PrefetchProxyCanaryCheckerClient}"
enum="NetErrorCodes" expires_after="2024-09-01">
<owner>[email protected]</owner>
<owner>[email protected]</owner>
<summary>
Records the net error of a completed or timed out probe. Note that if a HTTP
response does not occur within the probe's TTL, when a sample will also be
added to the ERR_TIMED_OUT bucket.
</summary>
<token key="PrefetchProxyCanaryCheckerClient"
variants="PrefetchProxyCanaryCheckerClient"/>
</histogram>
<histogram
name="PrefetchProxy.CanaryChecker.NumAttemptsBeforeSuccess.{PrefetchProxyCanaryCheckerClient}"
units="count" expires_after="2024-09-01">
<owner>[email protected]</owner>
<owner>[email protected]</owner>
<summary>
Records the number of attempts that are made to achieve a successful canary
check. This is recorded every time we make a canary check and the result is
a success. In particular, this means this is no recorded when a result was
already cached or when the check attempt fails after exhausting its retries.
This metric is 1-based so if a probe succeeds the first time, a sample of 1
will be recorded.
</summary>
<token key="PrefetchProxyCanaryCheckerClient"
variants="PrefetchProxyCanaryCheckerClient"/>
</histogram>
<histogram
name="PrefetchProxy.CanaryChecker.TimeUntilFailure.{PrefetchProxyCanaryCheckerClient}"
units="ms" expires_after="2024-09-01">
<owner>[email protected]</owner>
<owner>[email protected]</owner>
<summary>
Records the amount of time spent working on a single probe attempt to get to
a failed state. Recorded every time a probe fails.
</summary>
<token key="PrefetchProxyCanaryCheckerClient"
variants="PrefetchProxyCanaryCheckerClient"/>
</histogram>
<histogram
name="PrefetchProxy.CanaryChecker.TimeUntilSuccess.{PrefetchProxyCanaryCheckerClient}"
units="ms" expires_after="2024-09-01">
<owner>[email protected]</owner>
<owner>[email protected]</owner>
<summary>
Records the amount of time spent working on a single probe attempt to get to
a successful state. Recorded every time a probe succeeds.
</summary>
<token key="PrefetchProxyCanaryCheckerClient"
variants="PrefetchProxyCanaryCheckerClient"/>
</histogram>
<histogram name="PrefetchProxy.Prefetch.ExistingPrefetchWithMatchingURL"
enum="Boolean" expires_after="2024-01-14">
<owner>[email protected]</owner>
<owner>[email protected]</owner>
<owner>[email protected]</owner>
<summary>
Records whether or not there was an existing prefetch with a matching URL
from a different referring document when a new prefetch is requested. This
is recorded everytime a prefetch is requested.
</summary>
</histogram>
<histogram name="PrefetchProxy.Prefetch.Mainframe.BodyLength" units="bytes"
expires_after="2024-09-01">
<owner>[email protected]</owner>
<owner>[email protected]</owner>
<summary>
Records the response body length as cached in memory encountered when
isolated prefetching a mainframe HTML resource from the Google Search Result
Page. Recorded for non-network error prefetches only.
</summary>
</histogram>
<histogram name="PrefetchProxy.Prefetch.Mainframe.ConnectTime" units="ms"
expires_after="2024-07-21">
<owner>[email protected]</owner>
<owner>[email protected]</owner>
<owner>[email protected]</owner>
<summary>
Records the time taken to establish a socket connection when isolated
prefetching a mainframe HTML resource from the Google Search Result Page.
Recorded for non-network error prefetches only.
</summary>
</histogram>
<histogram name="PrefetchProxy.Prefetch.Mainframe.CookiesToCopy" units="count"
expires_after="2024-09-01">
<owner>[email protected]</owner>
<owner>[email protected]</owner>
<summary>
Records the number of cookies that needed to be copied from the prefetch
navigation to the user's profile after a prefetched link is navigated to.
</summary>
</histogram>
<histogram name="PrefetchProxy.Prefetch.Mainframe.NetError"
enum="NetErrorCodes" expires_after="2024-09-01">
<owner>[email protected]</owner>
<owner>[email protected]</owner>
<summary>
Records the Net Error encountered when isolated prefetching a mainframe HTML
resource from the Google Search Result Page. Recorded for every completed
prefetch.
</summary>
</histogram>
<histogram name="PrefetchProxy.Prefetch.Mainframe.RespCode"
enum="HttpResponseCode" expires_after="2025-01-26">
<owner>[email protected]</owner>
<owner>[email protected]</owner>
<summary>
Records the HTTP response code encountered isolated prefetching a mainframe
HTML resource from the Google Search Result Page. Recorded for non-network
error prefetches only. Redirects are not included here.
</summary>
</histogram>
<histogram name="PrefetchProxy.Prefetch.Mainframe.RetryAfter" units="ms"
expires_after="2024-09-01">
<owner>[email protected]</owner>
<owner>[email protected]</owner>
<summary>
Records the duration of a Retry-After header on a 503 response to a
mainframe prefetch request.
</summary>
</histogram>
<histogram name="PrefetchProxy.Prefetch.Mainframe.TotalTime" units="ms"
expires_after="2025-01-05">
<owner>[email protected]</owner>
<owner>[email protected]</owner>
<summary>
Records the total time taken when isolated prefetching a mainframe HTML
resource from the Google Search Result Page. Recorded for successful
non-network error prefetches only.
</summary>
</histogram>
<histogram
name="PrefetchProxy.Prefetch.NumExistingEligiblePrefetchWithMatchingURL"
units="count" expires_after="2024-02-04">
<owner>[email protected]</owner>
<owner>[email protected]</owner>
<summary>
Records the number of existing eligible prefetches with a matching URL from
a different referring document when a new prefetch is requested. This is
only recorded for prefetches where there is at least one existing prefetch
with a matching URL.
</summary>
</histogram>
<histogram name="PrefetchProxy.Prefetch.NumExistingPrefetchWithMatchingURL"
units="count" expires_after="2024-01-14">
<owner>[email protected]</owner>
<owner>[email protected]</owner>
<summary>
Records the number of existing prefetches with a matching URL from a
different referring document when a new prefetch is requested. This is
recorded everytime a prefetch is requested.
</summary>
</histogram>
<histogram
name="PrefetchProxy.Prefetch.NumExistingPrefetchWithMatchingURLAndReferrer"
units="count" expires_after="2024-02-04">
<owner>[email protected]</owner>
<owner>[email protected]</owner>
<summary>
Records the number of existing prefetches with a matching referring URL and
matching prefetch URL from a different referring document when a new
prefetch is requested. This is only recorded for prefetches where there is
at least one existing prefetch with a matching URL.
</summary>
</histogram>
<histogram
name="PrefetchProxy.Prefetch.NumExistingPrefetchWithMatchingURLAndRenderFrameHost"
units="count" expires_after="2024-02-04">
<owner>[email protected]</owner>
<owner>[email protected]</owner>
<summary>
Records the number of existing prefetches with a matching referring render
frame host and matching prefetch URL from a different referring document
when a new prefetch is requested. This case can occur if and only if there
was a same origin navigation that re-used the same render frame host and
both pages requested to prefetch the same URL. This is only recorded for
prefetches where there is at least one existing prefetch with a matching
URL.
</summary>
</histogram>
<histogram
name="PrefetchProxy.Prefetch.NumExistingServablePrefetchWithMatchingURL"
units="count" expires_after="2024-02-04">
<owner>[email protected]</owner>
<owner>[email protected]</owner>
<summary>
Records the number of existing prefetches with a successfully completed
prefetched responses and matching URL from a different referring document
when a new prefetch is requested. This is only recorded for prefetches where
there is at least one existing prefetch with a matching URL.
</summary>
</histogram>
<histogram name="PrefetchProxy.Prefetch.RedirectChainSize" units="count"
expires_after="2025-01-05">
<owner>[email protected]</owner>
<owner>[email protected]</owner>
<owner>[email protected]</owner>
<summary>
The redirect chain size of a prefetch. This histogram is recorded once for
each prefetch.
</summary>
</histogram>
<histogram name="PrefetchProxy.Prefetch.StreamingURLLoaderFinalStatus"
enum="PrefetchStreamingURLLoaderStatus" expires_after="2025-01-05">
<owner>[email protected]</owner>
<owner>[email protected]</owner>
<summary>
Records the final status of the PrefetchStreamingURLLoader used to request
the prefetch.
This is recorded once for each prefetch that is requested using a streaming
URL loader. It is recorded when the corresponding PrefetchResponseReader is
deleted which can be when: 1) the URL loader is canceled, 2) the URL loader
completed serving the prefetch, or 3) the prefetch was deleted and not used.
</summary>
</histogram>
<histogram name="PrefetchProxy.Proxy.Fallback.NetError" enum="NetErrorCodes"
expires_after="2024-04-25">
<owner>[email protected]</owner>
<owner>[email protected]</owner>
<summary>
Records the Net Error encountered when Chrome did a fallback from the
prefetch proxy. Recorded only on fallbacks.
</summary>
</histogram>
<histogram name="PrefetchProxy.Proxy.RespCode" enum="HttpResponseCode"
expires_after="2025-02-23">
<owner>[email protected]</owner>
<owner>[email protected]</owner>
<summary>
Warning: this histogram was expired from 2024-03-17 to 2024-08-20; data may
be missing.
Records the HTTP response code encountered when connecting to the prefetch
proxy CONNECT tunnel. Recorded every time Chrome gets CONNECT tunnel
response headers.
</summary>
</histogram>
<histogram name="PrefetchProxy.Redirect.NetworkContextStateTransition"
enum="PrefetchRedirectNetworkContextTransition" expires_after="2025-01-05">
<owner>[email protected]</owner>
<owner>[email protected]</owner>
<summary>
The network context transition required to handle a redirect while
prefetching. Prefetches require an isolated network context if user data
cannot be included in the prefetch. Otherwise the prefetch is made in the
default network context. This histogram is recorded for every redirect.
</summary>
</histogram>
<histogram name="PrefetchProxy.Redirect.Result" enum="PrefetchRedirectResult"
expires_after="2025-01-05">
<owner>[email protected]</owner>
<owner>[email protected]</owner>
<summary>
The result of receiving a redirect while prefetching. This histogram is
recorded for every redirect.
</summary>
</histogram>
<histogram name="PrefetchProxy.SpareRenderer.CountStartedOnSRP" units="count"
expires_after="2024-09-01">
<owner>[email protected]</owner>
<owner>[email protected]</owner>
<summary>
Records the number of spare renderers that were attempted to be started on
the SRP, when the feature param is enabled.
</summary>
</histogram>
</histograms>
</histogram-configuration>
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