message: Cache boost sources
  Summary:
  Pull Request resolved:
  Avoid hitting the boost servers, which have been flaky, lately.
diff: @@ -20,11 +20,27 @@ orbs:
  commands:
  # Setup. Includes boost.
  base-build-setup:
  + parameters:
  + save_boost_cache:
  + type: boolean
  + default: false
  steps:
  + # It is OK to generically restore boost, even if it is not used.
  + - restore_cache:
  + keys:
  + - boost-1-71-0-v1
  - run:
  name: Setup
  command: |
  sudo ./setup_oss_toolchain.sh
  + # Only save the cache when asked, e.g., hopefully when it was populated.
  + - when:
  + condition: << parameters.save_boost_cache >>
  + steps:
  + - save_cache:
  + paths:
  + - boost_cache
  + key: boost-1-71-0-v1
  # For testing, need additional dependencies not provided by the image.
  test-build-setup:
  @@ -151,8 +167,12 @@ commands:
  configure_extra:
  default: ""
  type: string
  + save_boost_cache:
  + type: boolean
  + default: false
  steps:
  - - base-build-setup
  + - base-build-setup:
  + save_boost_cache: << parameters.save_boost_cache >>
  - test-build-setup
  - configure-and-build-w-make:
  @@ -166,8 +186,12 @@ commands:
  configure_extra:
  default: ""
  type: string
  + save_boost_cache:
  + type: boolean
  + default: false
  steps:
  - - base-build-setup
  + - base-build-setup:
  + save_boost_cache: << parameters.save_boost_cache >>
  - test-build-setup-sdk
  - configure-and-build-w-make:
  @@ -224,7 +248,8 @@ jobs:
  resource_class: large
  steps:
  - checkout
  - - setup-build-and-test-w-make
  + - setup-build-and-test-w-make:
  + save_boost_cache: true
  build-deb_stable:
  docker:
  