build: speed up windows source retrieval (#20955)

* ci: speed up src retrieval

* Don't save zip on ia32

* Update external binaries if src zip already exists

* Apply suggestions from code review

Co-Authored-By: Jeremy Apthorp <jeremya@chromium.org>

* Update appveyor.yml

appveyor.yml

@@ -76,7 +76,30 @@ build_script:
       --unmanaged
       %GCLIENT_EXTRA_ARGS%
       "https://github.com/electron/electron"
-  - gclient sync --with_branch_heads --with_tags --reset
+  - ps: >-
+      if ($env:GN_CONFIG -eq 'release') {
+        gclient sync --with_branch_heads --with_tags --reset
+      } else {
+        cd src\electron
+        node script\generate-deps-hash.js
+        $depshash = Get-Content .\.depshash -Raw 
+        $zipfile = "Z:\$depshash.7z"
+        cd ..\..
+        if (Test-Path -Path $zipfile) {
+          # file exists, unzip and then gclient sync
+          7z x -y $zipfile -mmt=30 -aoa
+          # update external binaries
+          python src/electron/script/update-external-binaries.py
+        } else {    
+          # file does not exist, gclient sync, then zip
+          gclient sync --with_branch_heads --with_tags --reset
+          if ($env:TARGET_ARCH -ne 'ia32') {
+            # archive current source for future use 
+            # only run on x64/woa to avoid contention saving
+            7z a $zipfile src -xr!android_webview -xr!electron -xr'!*\.git' -xr!third_party\WebKit\LayoutTests! -xr!third_party\blink\web_tests -xr!third_party\blink\perf_tests -slp -t7z -mmt=30
+          }
+        }
+      }
   - cd src
   - ps: $env:BUILD_CONFIG_PATH="//electron/build/args/%GN_CONFIG%.gn"
   - gn gen out/Default "--args=import(\"%BUILD_CONFIG_PATH%\") %GN_EXTRA_ARGS% cc_wrapper=\"%SCCACHE_PATH%\""