feat: server-side SDK (#160)

This commit contains the C++ server-side SDK, omitting any persistent store capability. It modifies the internals of the client-side SDK in backwards compatible ways, and should trigger a client-side release. 

Followup commits should remove the server-side branch from CI.
---------

Co-authored-by: Ryan Lamb <[email protected]>
Co-authored-by: Molly <[email protected]>

Author: 3 people

.clang-tidy

@@ -1,5 +1,5 @@
 ---
 CheckOptions:
   - { key: readability-identifier-length.IgnoredParameterNames,   value: 'i|j|k|c|os|it' }
-  - { key: readability-identifier-length.IgnoredVariableNames, value: 'ec|id' }
+  - { key: readability-identifier-length.IgnoredVariableNames, value: 'ec|id|it' }
   - { key: readability-identifier-length.IgnoredLoopCounterNames,   value: 'i|j|k|c|os|it' }

.github/workflows/client.yml

@@ -6,7 +6,7 @@ on:
     paths-ignore:
       - '**.md' #Do not need to run CI for markdown changes.
   pull_request:
-    branches: [ main ]
+    branches: [ main, server-side ]
     paths-ignore:
       - '**.md'
 
@@ -16,12 +16,12 @@ jobs:
     env:
       # Port the test service (implemented in this repo) should bind to.
       TEST_SERVICE_PORT: 8123
-      TEST_SERVICE_BINARY: ./build/contract-tests/sdk-contract-tests/sdk-tests
+      TEST_SERVICE_BINARY: ./build/contract-tests/client-contract-tests/client-tests
     steps:
       - uses: actions/checkout@v3
       - uses: ./.github/actions/ci
         with:
-          cmake_target: sdk-tests
+          cmake_target: client-tests
           run_tests: false
       - name: 'Launch test service as background task'
         run: $TEST_SERVICE_BINARY $TEST_SERVICE_PORT 2>&1 &
@@ -36,7 +36,7 @@ jobs:
       - uses: ./.github/actions/ci
         with:
           cmake_target: launchdarkly-cpp-client
-  build-test-mac:
+  build-test-client-mac:
     runs-on: macos-12
     steps:
       - run: |
@@ -50,7 +50,7 @@ jobs:
         with:
           cmake_target: launchdarkly-cpp-client
           platform_version: 12
-  build-test-windows:
+  build-test-client-windows:
     runs-on: windows-2022
     steps:
       - name: Upgrade OpenSSL

.github/workflows/common.yml

@@ -6,12 +6,12 @@ on:
     paths-ignore:
       - '**.md' #Do not need to run CI for markdown changes.
   pull_request:
-    branches: [ main ]
+    branches: [ main, server-side ]
     paths-ignore:
       - '**.md'
 
 jobs:
-  build-test:
+  build-test-common:
     runs-on: ubuntu-22.04
     steps:
       - uses: actions/checkout@v3

.github/workflows/cpp-linter.yml

@@ -7,7 +7,7 @@ on:
   push:
     branches: [ "main" ]
   pull_request:
-    branches: [ "main" ]
+    branches: [ "main", server-side  ]
 
 jobs:
   cpp-linter:

.github/workflows/internal.yml

@@ -6,12 +6,12 @@ on:
     paths-ignore:
       - '**.md' #Do not need to run CI for markdown changes.
   pull_request:
-    branches: [ main ]
+    branches: [ main, server-side  ]
     paths-ignore:
       - '**.md'
 
 jobs:
-  build-test:
+  build-test-internal:
     runs-on: ubuntu-22.04
     steps:
       - uses: actions/checkout@v3

.github/workflows/server.yml

@@ -0,0 +1,79 @@
+name: libs/server-sdk
+
+on:
+  push:
+    branches: [ main ]
+    paths-ignore:
+      - '**.md' #Do not need to run CI for markdown changes.
+  pull_request:
+    branches: [ main, server-side ]
+    paths-ignore:
+      - '**.md'
+
+jobs:
+  contract-tests:
+    runs-on: ubuntu-22.04
+    env:
+      # Port the test service (implemented in this repo) should bind to.
+      TEST_SERVICE_PORT: 8123
+      TEST_SERVICE_BINARY: ./build/contract-tests/server-contract-tests/server-tests
+    steps:
+      - uses: actions/checkout@v3
+      - uses: ./.github/actions/ci
+        with:
+          cmake_target: server-tests
+          run_tests: false
+      - name: 'Launch test service as background task'
+        run: $TEST_SERVICE_BINARY $TEST_SERVICE_PORT 2>&1 &
+      - uses: ./.github/actions/contract-tests
+        with:
+          # Inform the test harness of test service's port.
+          test_service_port: ${{ env.TEST_SERVICE_PORT }}
+          extra_params: '-skip-from ./contract-tests/server-contract-tests/test-suppressions.txt'
+  build-test-server:
+    runs-on: ubuntu-22.04
+    steps:
+      - uses: actions/checkout@v3
+      - uses: ./.github/actions/ci
+        with:
+          cmake_target: launchdarkly-cpp-server
+  build-test-server-mac:
+    runs-on: macos-12
+    steps:
+      - run: |
+          echo "OPENSSL_ROOT_DIR=$(brew --prefix openssl@3)" >> "$GITHUB_ENV"
+          # For debugging
+          echo "OPENSSL_ROOT_DIR=$(brew --prefix openssl@3)"
+      - uses: actions/checkout@v3
+      - uses: ./.github/actions/ci
+        env:
+          OPENSSL_ROOT_DIR: ${{ env.OPENSSL_ROOT_DIR }}
+        with:
+          cmake_target: launchdarkly-cpp-server
+          platform_version: 12
+  build-test-server-windows:
+    runs-on: windows-2022
+    steps:
+      - name: Upgrade OpenSSL
+        shell: bash
+        run: |
+          choco upgrade openssl --no-progress
+      - name: Determine OpenSSL Installation Directory
+        shell: bash
+        run: |
+          if [ -d "C:\Program Files\OpenSSL-Win64" ]; then
+            echo "OPENSSL_ROOT_DIR=C:\Program Files\OpenSSL-Win64" >> "$GITHUB_ENV"
+          else
+            echo "OPENSSL_ROOT_DIR=C:\Program Files\OpenSSL" >> "$GITHUB_ENV"
+          fi
+      - uses: actions/checkout@v3
+      - uses: ilammy/msvc-dev-cmd@v1
+      - uses: ./.github/actions/ci
+        env:
+          OPENSSL_ROOT_DIR: ${{ env.OPENSSL_ROOT_DIR }}
+          BOOST_LIBRARY_DIR: 'C:\local\boost_1_81_0\lib64-msvc-14.3'
+          BOOST_LIBRARYDIR: 'C:\local\boost_1_81_0\lib64-msvc-14.3'
+        with:
+          cmake_target: launchdarkly-cpp-client
+          platform_version: 2022
+          toolset: msvc

.github/workflows/sse.yml

@@ -11,7 +11,7 @@ on:
       - '**.md'
 
 jobs:
-  build-test:
+  build-test-sse:
     runs-on: ubuntu-22.04
     steps:
       - uses: actions/checkout@v3

CMakeLists.txt

@@ -127,6 +127,7 @@ add_subdirectory(libs/server-sent-events)
 # Built as static or shared depending on LD_BUILD_SHARED_LIBS variable.
 # This target "links" in common, internal, and sse as object libraries.
 add_subdirectory(libs/client-sdk)
+add_subdirectory(libs/server-sdk)
 
 if (LD_BUILD_CONTRACT_TESTS)
     message(STATUS "LaunchDarkly: building contract tests")

README.md

@@ -42,6 +42,40 @@ GoogleTest is used for testing.
 
 For information on integrating an SDK package please refer to the SDK specific README.
 
+## CMake Usage
+
+Various CMake options are available to customize the client/server SDK builds.
+
+| Option                    | Description                                                                            | Default            | Requires                                  |
+|---------------------------|----------------------------------------------------------------------------------------|--------------------|-------------------------------------------|
+| `BUILD_TESTING`           | Coarse-grained switch; turn off to disable all testing and only build the SDK targets. | On                 | N/A                                       |
+| `LD_BUILD_UNIT_TESTS`     | Whether C++ unit tests are built.                                                      | On                 | `BUILD_TESTING; NOT LD_BUILD_SHARED_LIBS` |
+| `LD_TESTING_SANITIZERS`   | Whether sanitizers should be enabled.                                                  | On                 | `LD_BUILD_UNIT_TESTS`                     |
+| `LD_BUILD_CONTRACT_TESTS` | Whether the contract test service (used in CI) is built.                               | Off                | `BUILD_TESTING`                           |
+| `LD_BUILD_EXAMPLES`       | Whether example apps (hello world) are built.                                          | On                 | N/A                                       |
+| `LD_BUILD_SHARED_LIBS`    | Whether the SDKs are built as static or shared libraries.                              | Off  (static lib)  | N/A                                       |
+| `LD_DYNAMIC_LINK_OPENSSL` | Whether OpenSSL be dynamically linked.                                                 | Off  (static link) | N/A                                       |
+
+**Note:** _if building the SDKs as shared libraries, then unit tests won't be able to link correctly since the SDK's C++
+symbols aren't exposed. To run unit tests, build a static library._
+
+Basic usage example:
+
+```bash
+mkdir -p build && cd build
+cmake -G"Unix Makefiles" ..
+```
+
+Slightly more advanced example - build shared libraries, and don't build any of the testing components:
+
+```bash
+mkdir -p build  && cd build
+cmake -G"Unix Makefiles" -DLD_BUILD_SHARED_LIBS=On -DBUILD_TESTING=Off ..
+```
+
+The example uses `make`, but you might instead use [Ninja](https://ninja-build.org/),
+MSVC, [etc.](https://cmake.org/cmake/help/latest/manual/cmake-generators.7.html)
+
 ## LaunchDarkly overview
 
 [LaunchDarkly](https://www.launchdarkly.com) is a feature management platform that serves trillions of feature flags
@@ -76,7 +110,8 @@ our [contributing guidelines](CONTRIBUTING.md) for instructions on how to contri
     - Grant access to certain features based on user attributes, like payment plan (eg: users on the ‘gold’ plan get
       access to more features than users in the ‘silver’ plan). Disable parts of your application to facilitate
       maintenance, without taking everything offline.
-- LaunchDarkly provides feature flag SDKs for a wide variety of languages and technologies. Read [our documentation](https://docs.launchdarkly.com/sdk) for a complete list.
+- LaunchDarkly provides feature flag SDKs for a wide variety of languages and technologies.
+  Read [our documentation](https://docs.launchdarkly.com/sdk) for a complete list.
 - Explore LaunchDarkly
     - [launchdarkly.com](https://www.launchdarkly.com/ 'LaunchDarkly Main Website') for more information
     - [docs.launchdarkly.com](https://docs.launchdarkly.com/ 'LaunchDarkly Documentation') for our documentation and SDK

architecture/event_processor.md

@@ -0,0 +1,145 @@
+# Analytic Event Processor
+
+The Event Processor is responsible for consuming, batching, and delivering events generated
+by the server and client-side LaunchDarkly SDKs.
+
+```mermaid
+classDiagram
+    IEventProcessor <|-- NullEventProcessor
+    IEventProcessor <|-- AsioEventProcessor
+
+    AsioEventProcessor *-- LRUCache
+    AsioEventProcessor *-- Outbox
+    AsioEventProcessor *-- WorkerPool
+    AsioEventProcessor *-- Summarizer
+
+    RequestWorker *-- EventBatch
+    WorkerPool *-- "5" RequestWorker
+
+    TrackEvent -- TrackEventParams: (alias)
+    InputEvent *-- IdentifyEventParams
+    InputEvent *-- FeatureEventParams
+    InputEvent *-- TrackEventParams
+
+
+    OutputEvent *-- IndexEvent
+    OutputEvent *-- FeatureEvent
+    OutputEvent *-- DebugEvent
+    OutputEvent *-- IdentifyEvent
+    OutputEvent *-- TrackEvent
+
+    EventBatch --> Outbox: Pulls individual events from..
+    EventBatch --> Summarizer: Pulls summary events from..
+
+    IEventProcessor --> InputEvent
+    Outbox --> OutputEvent
+
+    Summarizer --> FeatureEventParams
+
+
+    class IEventProcessor {
+        <<interface>>
+        +SendAsync(InputEvent event) void
+        +FlushAsync() void
+        +ShutdownAsync() void
+    }
+
+    class NullEventProcessor {
+
+    }
+
+    class AsioEventProcessor {
+
+    }
+
+    class EventBatch {
+        +const Count() size_t
+        +const Request() network:: HttpRequest
+        +const Target() std:: string
+    }
+
+    class LRUCache {
+        +Notice(std:: string value) bool
+        +const Size() size_t
+        +Clear() void
+    }
+
+    class Outbox {
+        +PushDiscardingOverflow(std:: vector~OutputEvent~ events) bool
+        +Consume() std:: vector~OutputEvent~
+        +const Empty() bool
+    }
+
+    class RequestWorker {
+        +const Available() bool
+        +AsyncDeliver(EventBatch, delivery_callback)
+    }
+
+    class WorkerPool {
+        +Get(worker_callback) void
+    }
+
+    class Summarizer {
+        +Update(FeatureEventParams) void
+        +Finish()
+        +const StartTime() Time
+        +const EndTime() Time
+    }
+
+%% note: the 'namespace' feature isn't supported on Github yet
+%% namespace events { 
+    class InputEvent {
+        +std:: variant
+    }
+
+
+    class OutputEvent {
+        +std:: variant
+    }
+
+    class FeatureEventParams {
+
+    }
+
+    class IdentifyEventParams {
+
+    }
+
+    class TrackEventParams {
+
+    }
+
+    class FeatureEvent {
+
+    }
+
+    class DebugEvent {
+
+    }
+
+    class IdentifyEvent {
+
+    }
+
+    class IndexEvent {
+
+    }
+
+    class TrackEvent {
+
+    }
+
+%% }
+```
+
+### Notes
+
+SDKs may be configured to disable events, so `NullEventProcessor` is made available. This component accepts
+events generated
+by the SDK and discards them.
+
+If events are enabled, SDKs use the `AsioEventProcessor` implementation, which is an asynchronous processor
+utilizing `boost::asio`.
+
+Most event definitions are shared between the server and client-side SDKs. Unique to the server-side SDK
+is `IndexEvent`.