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      1 Skia Gold
      2 =========
      3 
      4 Overview
      5 --------
      6 
      7 Gold is a web application that compares the images produced by our bots against
      8 known baseline images.  
      9 Key features:  
     10 
     11 * Baselines are managed in Gold outside of Git, but in lockstep with Git commits.
     12 * Each commit creates >500k images.
     13 * Deviations from the baseline are triaged after a CL lands and images are triaged
     14   as either `positive` or `negative`. If a CL causes Skia to break it is reverted
     15   or an additional CL is landed to fix the problem.
     16 * We test across a range of dimensions, e.g.:
     17 
     18   - OS (Windows, Linux, Mac, Android, iOS)
     19   - Architectures (Intel, ARM)
     20   - Backends (CPU, OpenGL, Vulkan etc.)
     21   - etc.
     22 
     23 * Written in Go, Polymer and deployed on the Google Cloud.  The code
     24   is in the [Skia Infra Repository](https://github.com/google/skia-buildbot).
     25 
     26 Recommended Workflows
     27 ---------------------
     28 ### How to best use Gold for commonly faced problems ###
     29 
     30 These instructions will refer to various views which are accessible via the left
     31 navigation on [gold.skia.org](https://gold.skia.org/).  
     32 View access is public, triage access is granted to
     33 Skia contributors.  You must be logged in to triage.
     34 
     35 Problem #1: As sheriff, I need to triage and assign many incoming new images.
     36 -------------------------------------------------------------------------------
     37 Solution today:
     38 
     39 *   Access the By Blame view to see digests needing triage and associated
     40     owners/CLs
     41     +   Only untriaged digests will be shown by default
     42     +   Blame is not sorted in any particular order
     43     +   Digests are clustered by runs and the most minimal set of blame
     44 
     45 <img src=BlameView.png style="margin-left:30px" align="left" width="800"/> <br clear="left">
     46 
     47 *   Select digests for triage
     48     +   Digests will be listed in order with largest difference first
     49     +   Click to open the digest view with detailed information
     50 
     51 <img src=Digests.png style="margin-left:40px" align="left" width="780"/> <br clear="left">
     52 
     53 *   Open bugs for identified owner(s)
     54     +   The digest detail view has a link to open a bug from the UI
     55     +   Via the Gold UI or when manually entering a bug, copy the full URL of
     56         single digest into a bug report
     57     +   The URL reference to the digest in Issue Tracker will link the bug to
     58         the digest in Gold
     59 
     60 <img src="IssueHighlight.png" style="margin-left:60px" align="left" width="720" border=1/> <br clear="left">
     61 
     62 <br>
     63 
     64 Future improvements:
     65 
     66 *   Smarter, more granular blamelist
     67 
     68 <br>
     69 
     70 Problem #2: As a developer, I need to land a CL that may change many images.
     71 ----------------------------------------------------------------------------
     72 To find your results:
     73 
     74 *   Immediately following commit, access the By Blame view to find untriaged
     75     digest groupings associated with your ID
     76 *   Click on one of the clusters including your CL to triage
     77 *   Return to the By Blame view to walk through all untriaged digests involving
     78     your change
     79 *   Note:  It is not yet implemented in the UI but possible to filter the view
     80     by CL.  Delete hashes in the URL to only include the hash for your CL.
     81 
     82 <img src=BlameView.png style="margin-left:30px" align="left" width="800"/> <br clear="left">
     83 
     84 To rebaseline images:
     85 
     86 *   Access the Ignores view and create a new, short-interval (hours) ignore for
     87     the most affected configuration(s)
     88 
     89 <img src=Ignores.png style="margin-left:30px" align="left" width="800"/> <br clear="left">
     90 
     91 
     92 *   Click on the Ignore to bring up a search view filtered by the affected
     93     configuration(s)
     94 *   Mark untriaged images as positive (or negative if appropriate)
     95 *   Follow one of two options for handling former positives:
     96     +   Leave former positives as-is and let them fall off with time if there is
     97         low risk of recurrence
     98     +   Mark former positives as negative if needed to verify the change moving
     99         forward
    100 
    101 Future improvements:
    102 
    103 *   Trybot support prior to commit, with view limited to your CL  
    104 *   Pre-triage prior to commit that will persist when the CL lands
    105 
    106 <br>
    107 
    108 Problem #3: As a developer or infrastructure engineer, I need to add a new or updated config.
    109 ---------------------------------------------------------------------------------------------
    110 (ie: new bot, test mode, environment change)
    111 
    112 Solution today:
    113 
    114 *   Follow the process for rebaselining images:
    115     +   Wait for the bot/test/config to be committed and show up in the Gold UI
    116     +   Access the Ignores view and create a short-interval ignore for the
    117         configuration(s)
    118     +   Triage the ignores for that config to identify positive images
    119     +   Delete the ignore
    120 
    121 Future improvements:
    122 
    123 *   Introduction of a new or updated test can make use of try jobs and pre-triage.  
    124 *   New configs may be able to use these features as well.
    125 
    126 <br>
    127 
    128 Problem #4: As a developer, I need to analyze the details of a particular image digest.
    129 ---------------------------------------------------------------------------------------
    130 Solution:
    131 
    132 *   Access the By Test view
    133 
    134 <img src=ByTest.png style="margin-left:30px" align="left" width="800"/> <br clear="left">
    135 
    136 *   Click the magnifier to filter by configuration
    137 *   Access the Cluster view to see the distribution of digest results
    138     +   Use control-click to select and do a direct compare between data points
    139     +   Click on configurations under parameters to highlight data points and
    140         compare
    141 
    142 <img src=ClusterConfig.png style="margin-left:30px" align="left" width="800"/> <br clear="left">
    143 
    144 *   Access the Grid view to see NxN diffs
    145 
    146 <img src=Grid.png style="margin-left:30px" align="left" width="800"/> <br clear="left">
    147 
    148 *   Access the Dot diagram to see history of commits for the trace
    149     +   Each dot represents a commit
    150     +   Each line represents a configuration
    151     +   Dot colors distinguish between digests
    152 
    153 <img src=DotDiagram.png style="margin-left:30px" align="left" width="800"/> <br clear="left">
    154 
    155 <br>
    156 
    157 Future improvements:
    158 
    159 *   Large diff display of image vs image
    160 
    161 <br>
    162 
    163 Problem #5: As a developer, I need to find results for a particular configuration.
    164 ----------------------------------------------------------------------------------
    165 Solution:
    166 
    167 *   Access the Search view
    168 *   Select any parameters desired to search across tests
    169 
    170 <img src=Search.png style="margin-left:30px" align="left" width="800"/> <br clear="left">
    171