opendev/gerrit
Code Issues Proposed changes

Lazy load HighlightJS library

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Previously, the HighlightJS library (HLJS) was being Vulcanized into the
PolyGerrit build, even if the library was not being used (for example if
the user does not navigate to a diff or has syntax highlighting disabled
in preferences). Because HLJS is a substantial file -- ranging in size
from 47KB to more than 455KB (ungizpped) depending on the build
environment, this is not ideal.

In order to lazy load a JS library:

1)  It needs to be copied into the built WAR file to be addressable, and
2)  It should not be Vulcanized into the built gr-app.js file.

Previously, the PolyGerrit build system supported copying and
non-vulcanizing exactly one JS library: namely webcomponents-lite.js.
This change generalizes the mechanism by which webcomponents is copied
and adds HLJS to that list. This satisfies **1**.

Furthermore, the GR-SYNTAX-LAYER is rewritten to dynamically import HLJS
in the `process` step by crafting a SCRIPT element and attaching it to
the local DOM. (Syntax processing is invoked only after entire diff is
rendered.) Code that depends on the library awaits this load before
using it. Thus, the conventional JS import can be removed from the
element's HTML and will not be recognized by the Vulcanize phase. This
satisfies **2**.

Tests are updated accordingly.

Bug: Issue 4298
Change-Id: I9a95d6d4c211cd8f1ca1bc4daec770b64b22b3d1
This commit is contained in:
Wyatt Allen
2016-08-01 15:23:50 -07:00
parent f1063a2690
commit db56a6f62c
4 changed files with 127 additions and 88 deletions
Download Patch File Download Diff File Expand all files Collapse all files

21
polygerrit-ui/app/BUCK
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@@ -14,7 +14,21 @@ APP_SRCS = glob(
'test/**',
] + WCT_TEST_PATTERNS + PY_TEST_PATTERNS)
WEBJS = 'bower_components/webcomponentsjs/webcomponents-lite.js'
# List libraries to be copied statically into the build. (i.e. Libraries not
# expected to be Vulcanized.)
WEB_JS_LIBS = [
('bower_components/webcomponentsjs', 'webcomponents-lite.js'),
('bower_components/highlightjs', 'highlight.min.js'),
]
# Map the static libraries to commands for the polygerrit_ui rule.
JS_LIBS_MKDIR_CMDS = []
JS_LIBS_UNZIP_CMDS = []
for lib in WEB_JS_LIBS:
JS_LIBS_MKDIR_CMDS.append('mkdir -p ' + lib[0])
path = lib[0] + '/' + lib[1]
cmd = 'unzip -p $(location //polygerrit-ui:polygerrit_components) %s>%s' % (path, path)
JS_LIBS_UNZIP_CMDS.append(cmd)
# TODO(dborowitz): Putting these rules in this package avoids having to handle
# the app/ prefix like we would have to if this were in the parent directory.
@@ -26,11 +40,12 @@ genrule(
cmd = ' && '.join([
'mkdir $TMP/polygerrit_ui',
'cd $TMP/polygerrit_ui',
'mkdir -p {fonts,elements,bower_components/webcomponentsjs}',
'mkdir -p {fonts,elements}',
' && '.join(JS_LIBS_MKDIR_CMDS),
'unzip -qd fonts $(location //polygerrit-ui:fonts)',
'unzip -qd elements $(location :gr-app)',
'cp -rp $SRCDIR/* .',
'unzip -p $(location //polygerrit-ui:polygerrit_components) %s>%s' % (WEBJS, WEBJS),
' && '.join(JS_LIBS_UNZIP_CMDS),
'cd $TMP',
'zip -9qr $OUT .',
]),