feat: server-side C bindings

examples/CMakeLists.txt

@@ -1,3 +1,6 @@
 add_subdirectory(hello-c-client)
 add_subdirectory(hello-cpp-client)
 add_subdirectory(hello-cpp-server)
+add_subdirectory(hello-c-server)
+
+add_subdirectory(client-and-server-coexistence)

examples/client-and-server-coexistence/CMakeLists.txt

@@ -0,0 +1,15 @@
+# Required for Apple Silicon support.
+cmake_minimum_required(VERSION 3.19)
+
+project(
+        LaunchDarklyCClientAndServerCoexistence
+        VERSION 0.1
+        DESCRIPTION "LaunchDarkly C Client-side and Server-side SDK coexistence in same application"
+        LANGUAGES C
+)
+
+set(THREADS_PREFER_PTHREAD_FLAG ON)
+find_package(Threads REQUIRED)
+
+add_executable(c-client-and-server main.c)
+target_link_libraries(c-client-and-server PRIVATE launchdarkly::client launchdarkly::server launchdarkly::sse launchdarkly::common Threads::Threads)

examples/client-and-server-coexistence/main.c

@@ -0,0 +1,46 @@
+/**
+ * This application intends to verify that the symbols from the
+ * client-side and server-side SDKs do not clash, thus enabling both SDKs to be
+ * used within the same application.
+ */
+
+#include <launchdarkly/client_side/bindings/c/sdk.h>
+#include <launchdarkly/server_side/bindings/c/sdk.h>
+
+#include <launchdarkly/client_side/bindings/c/config/builder.h>
+#include <launchdarkly/server_side/bindings/c/config/builder.h>
+
+#include <launchdarkly/bindings/c/context_builder.h>
+
+int main() {
+    LDContextBuilder context_builder = LDContextBuilder_New();
+    LDContextBuilder_AddKind(context_builder, "user", "example-user-key");
+    LDContextBuilder_Attributes_SetName(context_builder, "user", "Sandy");
+    LDContext context = LDContextBuilder_Build(context_builder);
+
+    LDClientConfigBuilder client_config_builder =
+        LDClientConfigBuilder_New("foo");
+    LDClientConfig client_config = NULL;
+
+    LDStatus client_config_status =
+        LDClientConfigBuilder_Build(client_config_builder, &client_config);
+
+    if (LDStatus_Ok(client_config_status)) {
+        LDClientSDK client_sdk = LDClientSDK_New(client_config, context);
+        LDClientSDK_Free(client_sdk);
+    }
+
+    LDServerConfigBuilder server_config_builder =
+        LDServerConfigBuilder_New("foo");
+    LDServerConfig server_config = NULL;
+
+    LDStatus server_config_status =
+        LDServerConfigBuilder_Build(server_config_builder, &server_config);
+
+    if (LDStatus_Ok(server_config_status)) {
+        LDServerSDK server_sdk = LDServerSDK_New(server_config);
+        LDServerSDK_Free(server_sdk);
+    }
+
+    return 0;
+}

examples/hello-c-client/main.c

@@ -29,7 +29,7 @@ int main() {
     LDClientConfigBuilder config_builder =
         LDClientConfigBuilder_New(MOBILE_KEY);
 
-    LDClientConfig config;
+    LDClientConfig config = NULL;
     LDStatus config_status =
         LDClientConfigBuilder_Build(config_builder, &config);
     if (!LDStatus_Ok(config_status)) {
@@ -44,7 +44,7 @@ int main() {
 
     LDClientSDK client = LDClientSDK_New(config, context);
 
-    bool initialized_successfully;
+    bool initialized_successfully = false;
     if (LDClientSDK_Start(client, INIT_TIMEOUT_MILLISECONDS,
                           &initialized_successfully)) {
         if (initialized_successfully) {

examples/hello-c-server/CMakeLists.txt

@@ -0,0 +1,15 @@
+# Required for Apple Silicon support.
+cmake_minimum_required(VERSION 3.19)
+
+project(
+        LaunchDarklyHelloCServer
+        VERSION 0.1
+        DESCRIPTION "LaunchDarkly Hello C Server-side SDK"
+        LANGUAGES C
+)
+
+set(THREADS_PREFER_PTHREAD_FLAG ON)
+find_package(Threads REQUIRED)
+
+add_executable(hello-c-server main.c)
+target_link_libraries(hello-c-server PRIVATE launchdarkly::server launchdarkly::sse launchdarkly::common Threads::Threads)

examples/hello-c-server/main.c

@@ -0,0 +1,78 @@
+#include <launchdarkly/server_side/bindings/c/config/builder.h>
+#include <launchdarkly/server_side/bindings/c/sdk.h>
+
+#include <launchdarkly/bindings/c/context_builder.h>
+
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+// Set SDK_KEY to your LaunchDarkly SKD key.
+#define SDK_KEY ""
+
+// Set FEATURE_FLAG_KEY to the feature flag key you want to evaluate.
+#define FEATURE_FLAG_KEY "my-boolean-flag"
+
+// Set INIT_TIMEOUT_MILLISECONDS to the amount of time you will wait for
+// the client to become initialized.
+#define INIT_TIMEOUT_MILLISECONDS 3000
+
+int main() {
+    if (!strlen(SDK_KEY)) {
+        printf(
+            "*** Please edit main.c to set SDK_KEY to your LaunchDarkly "
+            "SDK key first\n\n");
+        return 1;
+    }
+
+    LDServerConfigBuilder config_builder = LDServerConfigBuilder_New(SDK_KEY);
+
+    LDServerConfig config = NULL;
+    LDStatus config_status =
+        LDServerConfigBuilder_Build(config_builder, &config);
+    if (!LDStatus_Ok(config_status)) {
+        printf("error: config is invalid: %s", LDStatus_Error(config_status));
+        return 1;
+    }
+
+    LDServerSDK client = LDServerSDK_New(config);
+
+    bool initialized_successfully = false;
+    if (LDServerSDK_Start(client, INIT_TIMEOUT_MILLISECONDS,
+                          &initialized_successfully)) {
+        if (initialized_successfully) {
+            printf("*** SDK successfully initialized!\n\n");
+        } else {
+            printf("*** SDK failed to initialize\n");
+            return 1;
+        }
+    } else {
+        printf("SDK initialization didn't complete in %dms\n",
+               INIT_TIMEOUT_MILLISECONDS);
+        return 1;
+    }
+
+    LDContextBuilder context_builder = LDContextBuilder_New();
+    LDContextBuilder_AddKind(context_builder, "user", "example-user-key");
+    LDContextBuilder_Attributes_SetName(context_builder, "user", "Sandy");
+    LDContext context = LDContextBuilder_Build(context_builder);
+
+    bool flag_value =
+        LDServerSDK_BoolVariation(client, context, FEATURE_FLAG_KEY, false);
+
+    printf("*** Feature flag '%s' is %s for this user\n\n", FEATURE_FLAG_KEY,
+           flag_value ? "true" : "false");
+
+    // Here we ensure that the SDK shuts down cleanly and has a chance to
+    // deliver analytics events to LaunchDarkly before the program exits. If
+    // analytics events are not delivered, the user properties and flag usage
+    // statistics will not appear on your dashboard. In a normal long-running
+    // application, the SDK would continue running and events would be delivered
+    // automatically in the background.
+
+    LDContext_Free(context);
+    LDServerSDK_Free(client);
+
+    return 0;
+}

examples/hello-cpp-server/main.cpp

@@ -4,8 +4,8 @@
 #include <cstring>
 #include <iostream>
 
-// Set MOBILE_KEY to your LaunchDarkly mobile key.
-#define MOBILE_KEY ""
+// Set SDK_KEY to your LaunchDarkly SDK key.
+#define SDK_KEY ""
 
 // Set FEATURE_FLAG_KEY to the feature flag key you want to evaluate.
 #define FEATURE_FLAG_KEY "my-boolean-flag"
@@ -16,14 +16,14 @@
 
 using namespace launchdarkly;
 int main() {
-    if (!strlen(MOBILE_KEY)) {
+    if (!strlen(SDK_KEY)) {
         printf(
-            "*** Please edit main.cpp to set MOBILE_KEY to your LaunchDarkly "
-            "mobile key first\n\n");
+            "*** Please edit main.cpp to set SDK_KEY to your LaunchDarkly "
+            "SDK key first\n\n");
         return 1;
     }
 
-    auto config = server_side::ConfigBuilder(MOBILE_KEY).Build();
+    auto config = server_side::ConfigBuilder(SDK_KEY).Build();
     if (!config) {
         std::cout << "error: config is invalid: " << config.error() << '\n';
         return 1;

libs/client-sdk/include/launchdarkly/client_side/bindings/c/config/config.h

@@ -14,8 +14,8 @@ extern "C" {  // only need to export C interface if
 typedef struct _LDClientConfig* LDClientConfig;
 
 /**
- * Frees an unused configuration. Configurations passed into an LDClient must
- * not be be freed.
+ * Free an unused configuration. Configurations used to construct an LDClientSDK
+ * must not be be freed.
  *
  * @param config Config to free.
  */

libs/client-sdk/include/launchdarkly/client_side/bindings/c/sdk.h

@@ -13,6 +13,7 @@
 #include <launchdarkly/bindings/c/flag_listener.h>
 #include <launchdarkly/bindings/c/listener_connection.h>
 #include <launchdarkly/bindings/c/memory_routines.h>
+#include <launchdarkly/bindings/c/shared_function_argument_macro_definitions.h>
 #include <launchdarkly/bindings/c/status.h>
 #include <launchdarkly/bindings/c/value.h>
 
@@ -27,9 +28,6 @@ extern "C" {  // only need to export C interface if
 
 typedef struct _LDClientSDK* LDClientSDK;
 
-#define LD_NONBLOCKING 0
-#define LD_DISCARD_DETAIL NULL
-
 /**
  * Constructs a new client-side LaunchDarkly SDK from a configuration and
  * context.

libs/client-sdk/src/bindings/c/sdk.cpp

@@ -203,7 +203,6 @@ LDClientSDK_StringVariation(LDClientSDK sdk,
     LD_ASSERT_NOT_NULL(flag_key);
     LD_ASSERT_NOT_NULL(default_value);
 
-    // TODO: custom allocation / free routines
     return strdup(
         TO_SDK(sdk)->StringVariation(flag_key, default_value).c_str());
 }

libs/client-sdk/tests/client_c_bindings_test.cpp

@@ -49,7 +49,7 @@ TEST(ClientBindings, RegisterFlagListener) {
     ASSERT_TRUE(LDStatus_Ok(status));
 
     LDContextBuilder ctx_builder = LDContextBuilder_New();
-    LDContextBuilder_AddKind(ctx_builder, "`user", "shadow");
+    LDContextBuilder_AddKind(ctx_builder, "user", "shadow");
 
     LDContext context = LDContextBuilder_Build(ctx_builder);
 

libs/common/include/launchdarkly/bindings/c/shared_function_argument_macro_definitions.h

@@ -0,0 +1,8 @@
+/** @file */
+#pragma once
+
+/* Function should operate asynchronously. */
+#define LD_NONBLOCKING 0
+
+/* Function should discard evaluation details. */
+#define LD_DISCARD_DETAIL NULL

libs/common/include/launchdarkly/config/client.hpp

@@ -15,9 +15,7 @@ using SDK = config::shared::ClientSDK;
 using Defaults = config::shared::Defaults<SDK>;
 using AppInfoBuilder = config::shared::builders::AppInfoBuilder;
 using EndpointsBuilder = config::shared::builders::EndpointsBuilder<SDK>;
-
 using ConfigBuilder = config::shared::builders::ConfigBuilder<SDK>;
-
 using EventsBuilder = config::shared::builders::EventsBuilder<SDK>;
 using HttpPropertiesBuilder =
     config::shared::builders::HttpPropertiesBuilder<SDK>;

libs/common/include/launchdarkly/config/server.hpp

@@ -19,6 +19,7 @@ using EventsBuilder = config::shared::builders::EventsBuilder<SDK>;
 using HttpPropertiesBuilder =
     config::shared::builders::HttpPropertiesBuilder<SDK>;
 using DataSourceBuilder = config::shared::builders::DataSourceBuilder<SDK>;
+using LoggingBuilder = config::shared::builders::LoggingBuilder;
 using PersistenceBuilder = config::shared::builders::PersistenceBuilder<SDK>;
 
 using Config = config::Config<SDK>;