RUMM-2165: Add trace sampling for instrumented network requests

dd-sdk-android-glide/README.md

@@ -48,10 +48,12 @@ Doing so will automatically track Glide's network requests (creating both APM Tr
 @GlideModule
 class CustomGlideModule : 
     DatadogGlideModule(
-        listOf("example.com", "example.eu")
+        listOf("example.com", "example.eu"), traceSamplingRate = 20f
     )
 ```
 
+Network requests are sampled with an adjustable sampling rate. A sampling of 20% is applied by default.
+
 
 ## Contributing
 

dd-sdk-android-glide/apiSurface

@@ -1,5 +1,5 @@
 open class com.datadog.android.glide.DatadogGlideModule : com.bumptech.glide.module.AppGlideModule
-  constructor(List<String> = emptyList())
+  constructor(List<String> = emptyList(), Float = DEFAULT_SAMPLING_RATE)
   override fun registerComponents(android.content.Context, com.bumptech.glide.Glide, com.bumptech.glide.Registry)
   override fun applyOptions(android.content.Context, com.bumptech.glide.GlideBuilder)
   open fun getClientBuilder(): okhttp3.OkHttpClient.Builder

dd-sdk-android-glide/src/main/kotlin/com/datadog/android/glide/DatadogGlideModule.kt

@@ -33,10 +33,14 @@ import okhttp3.Request
  * - be wrapped in a Span and have trace id injected to get a full flame-graph in APM.
  * If no host provided the interceptor won't trace any OkHttp [Request], nor propagate tracing
  * information to the backend, but RUM Resource events will still be sent for each request.
+ * @param samplingRate the sampling rate for APM traces created for auto-instrumented
+ * requests. It must be a value between `0.0` and `100.0`. A value of `0.0` means no trace will
+ * be kept, `100.0` means all traces will be kept (default value is `20.0`).
  */
 open class DatadogGlideModule
 @JvmOverloads constructor(
-    private val firstPartyHosts: List<String> = emptyList()
+    private val firstPartyHosts: List<String> = emptyList(),
+    private val samplingRate: Float = DEFAULT_SAMPLING_RATE
 ) : AppGlideModule() {
 
     // region AppGlideModule
@@ -76,9 +80,13 @@ open class DatadogGlideModule
      */
     open fun getClientBuilder(): OkHttpClient.Builder {
         return OkHttpClient.Builder()
-            .addInterceptor((DatadogInterceptor(firstPartyHosts)))
+            .addInterceptor(DatadogInterceptor(firstPartyHosts, traceSamplingRate = samplingRate))
             .eventListenerFactory(DatadogEventListener.Factory())
     }
 
     // endregion
+
+    private companion object {
+        private const val DEFAULT_SAMPLING_RATE: Float = 20f
+    }
 }

dd-sdk-android/README.md

@@ -29,7 +29,7 @@ class SampleApplication : Application() {
 
 ### Setup for Europe
 
-If you're targetting our [Europe servers](https://datadoghq.eu), you can
+If you're targeting our [Europe servers](https://datadoghq.eu), you can
 initialize the library like this: 
 
 ```kotlin
@@ -139,12 +139,12 @@ do so by providing a map alongside the message, each entry being added as an att
 
 In Java you can do so as follows:
 ```java
-    mLogger.d(
+    Map<String, Object> attributes = new HashMap<>();
+    attributes.put("http.url", url);
+    logger.d(
             "onPageStarted",
             null, 
-            new HashMap<String, Object>() {{
-                put("http.url", url);
-            }}
+            attributes
     );
 ```
 

dd-sdk-android/apiSurface

@@ -52,8 +52,8 @@ class com.datadog.android.DatadogEventListener : okhttp3.EventListener
   class Factory : okhttp3.EventListener.Factory
     override fun create(okhttp3.Call): okhttp3.EventListener
 open class com.datadog.android.DatadogInterceptor : com.datadog.android.tracing.TracingInterceptor
-  constructor(List<String>, com.datadog.android.tracing.TracedRequestListener = NoOpTracedRequestListener(), com.datadog.android.rum.RumResourceAttributesProvider = NoOpRumResourceAttributesProvider())
-  constructor(com.datadog.android.tracing.TracedRequestListener = NoOpTracedRequestListener(), com.datadog.android.rum.RumResourceAttributesProvider = NoOpRumResourceAttributesProvider())
+  constructor(List<String>, com.datadog.android.tracing.TracedRequestListener = NoOpTracedRequestListener(), com.datadog.android.rum.RumResourceAttributesProvider = NoOpRumResourceAttributesProvider(), Float = DEFAULT_TRACE_SAMPLING_RATE)
+  constructor(com.datadog.android.tracing.TracedRequestListener = NoOpTracedRequestListener(), com.datadog.android.rum.RumResourceAttributesProvider = NoOpRumResourceAttributesProvider(), Float = DEFAULT_TRACE_SAMPLING_RATE)
   override fun intercept(okhttp3.Interceptor.Chain): okhttp3.Response
   override fun onRequestIntercepted(okhttp3.Request, io.opentracing.Span?, okhttp3.Response?, Throwable?)
   override fun canSendSpan(): Boolean
@@ -357,7 +357,7 @@ enum com.datadog.android.rum.RumErrorSource
   - AGENT
   - WEBVIEW
 class com.datadog.android.rum.RumInterceptor : com.datadog.android.DatadogInterceptor
-  constructor(List<String> = emptyList(), RumResourceAttributesProvider = NoOpRumResourceAttributesProvider())
+  constructor(List<String> = emptyList(), RumResourceAttributesProvider = NoOpRumResourceAttributesProvider(), Float = DEFAULT_TRACE_SAMPLING_RATE)
 interface com.datadog.android.rum.RumMonitor
   fun startView(Any, String, Map<String, Any?> = emptyMap())
   fun stopView(Any, Map<String, Any?> = emptyMap())
@@ -1439,8 +1439,8 @@ class com.datadog.android.tracing.AndroidTracer : com.datadog.opentracing.DDTrac
 interface com.datadog.android.tracing.TracedRequestListener
   fun onRequestIntercepted(okhttp3.Request, io.opentracing.Span, okhttp3.Response?, Throwable?)
 open class com.datadog.android.tracing.TracingInterceptor : okhttp3.Interceptor
-  constructor(List<String>, TracedRequestListener = NoOpTracedRequestListener())
-  constructor(TracedRequestListener = NoOpTracedRequestListener())
+  constructor(List<String>, TracedRequestListener = NoOpTracedRequestListener(), Float = DEFAULT_TRACE_SAMPLING_RATE)
+  constructor(TracedRequestListener = NoOpTracedRequestListener(), Float = DEFAULT_TRACE_SAMPLING_RATE)
   override fun intercept(okhttp3.Interceptor.Chain): okhttp3.Response
   protected open fun onRequestIntercepted(okhttp3.Request, io.opentracing.Span?, okhttp3.Response?, Throwable?)
   companion object 

dd-sdk-android/src/main/java/com/datadog/opentracing/propagation/DatadogHttpCodec.java

@@ -26,7 +26,6 @@ class DatadogHttpCodec {
   private static final String TRACE_ID_KEY = "x-datadog-trace-id";
   private static final String SPAN_ID_KEY = "x-datadog-parent-id";
   private static final String SAMPLING_PRIORITY_KEY = "x-datadog-sampling-priority";
-  private static final String SELECTED_FOR_SAMPLE_KEY = "x-datadog-sampled";
   private static final String ORIGIN_KEY = "x-datadog-origin";
 
   private DatadogHttpCodec() {
@@ -50,8 +49,6 @@ public void inject(final DDSpanContext context, final TextMapInject carrier) {
 
       // always use max sampling priority for Android traces
       carrier.put(SAMPLING_PRIORITY_KEY, "1");
-      // makes this request trace selected for sampling
-      carrier.put(SELECTED_FOR_SAMPLE_KEY, "1");
     }
   }
 

dd-sdk-android/src/main/kotlin/com/datadog/android/DatadogInterceptor.kt

@@ -6,10 +6,13 @@
 
 package com.datadog.android
 
+import androidx.annotation.FloatRange
 import com.datadog.android.core.configuration.Configuration
 import com.datadog.android.core.internal.CoreFeature
 import com.datadog.android.core.internal.net.FirstPartyHostDetector
 import com.datadog.android.core.internal.net.identifyRequest
+import com.datadog.android.core.internal.sampling.RateBasedSampler
+import com.datadog.android.core.internal.sampling.Sampler
 import com.datadog.android.core.internal.utils.devLogger
 import com.datadog.android.core.internal.utils.sdkLogger
 import com.datadog.android.rum.GlobalRum
@@ -65,8 +68,9 @@ import okhttp3.Response
  * ```
  *
  * @param tracedHosts a list of all the hosts that you want to be automatically tracked
- * by our APM [TracingInterceptor]. If no host provided the interceptor won't trace
- * any OkHttpRequest, nor propagate tracing information to the backend.
+ * by our APM [TracingInterceptor]. If no host provided (via this argument or global
+ * configuration [Configuration.Builder.setFirstPartyHosts]) the interceptor won't trace
+ * any [okhttp3.Request], nor propagate tracing information to the backend.
  * Please note that the host constraint will only be applied on the [TracingInterceptor] and we will
  * continue to dispatch RUM Resource events for each request without applying any host filtering.
  * @param tracedRequestListener which listens on the intercepted [okhttp3.Request] and offers
@@ -80,12 +84,14 @@ internal constructor(
     tracedRequestListener: TracedRequestListener,
     firstPartyHostDetector: FirstPartyHostDetector,
     internal val rumResourceAttributesProvider: RumResourceAttributesProvider,
+    traceSampler: Sampler,
     localTracerFactory: () -> Tracer
 ) : TracingInterceptor(
     tracedHosts,
     tracedRequestListener,
     firstPartyHostDetector,
     ORIGIN_RUM,
+    traceSampler,
     localTracerFactory
 ) {
 
@@ -97,24 +103,30 @@ internal constructor(
      * Requests made to a URL with any one of these hosts (or any subdomain) will:
      * - be considered a first party RUM Resource and categorised as such in your RUM dashboard;
      * - be wrapped in a Span and have trace id injected to get a full flame-graph in APM.
-     * If no host provided the interceptor won't trace any OkHttp [Request], nor propagate tracing
+     * If no host provided (via this argument or global configuration [Configuration.Builder.setFirstPartyHosts])
+     * the interceptor won't trace any OkHttp [Request], nor propagate tracing
      * information to the backend, but RUM Resource events will still be sent for each request.
      * @param tracedRequestListener which listens on the intercepted [okhttp3.Request] and offers
      * the possibility to modify the created [io.opentracing.Span].
      * @param rumResourceAttributesProvider which listens on the intercepted [okhttp3.Request]
      * and offers the possibility to add custom attributes to the RUM resource events.
+     * @param traceSamplingRate the sampling rate for APM traces created for auto-instrumented
+     * requests. It must be a value between `0.0` and `100.0`. A value of `0.0` means no trace will
+     * be kept, `100.0` means all traces will be kept (default value is `20.0`).
      */
     @JvmOverloads
     constructor(
         firstPartyHosts: List<String>,
         tracedRequestListener: TracedRequestListener = NoOpTracedRequestListener(),
         rumResourceAttributesProvider: RumResourceAttributesProvider =
-            NoOpRumResourceAttributesProvider()
+            NoOpRumResourceAttributesProvider(),
+        @FloatRange(from = 0.0, to = 100.0) traceSamplingRate: Float = DEFAULT_TRACE_SAMPLING_RATE
     ) : this(
         tracedHosts = firstPartyHosts,
         tracedRequestListener = tracedRequestListener,
         firstPartyHostDetector = CoreFeature.firstPartyHostDetector,
         rumResourceAttributesProvider = rumResourceAttributesProvider,
+        traceSampler = RateBasedSampler(traceSamplingRate / 100),
         localTracerFactory = { AndroidTracer.Builder().build() }
     )
 
@@ -126,17 +138,22 @@ internal constructor(
      * the possibility to modify the created [io.opentracing.Span].
      * @param rumResourceAttributesProvider which listens on the intercepted [okhttp3.Request]
      * and offers the possibility to add custom attributes to the RUM resource events.
+     * @param traceSamplingRate the sampling rate for APM traces created for auto-instrumented
+     * requests. It must be a value between `0.0` and `100.0`. A value of `0.0` means no trace will
+     * be kept, `100.0` means all traces will be kept (default value is `20.0`).
      */
     @JvmOverloads
     constructor(
         tracedRequestListener: TracedRequestListener = NoOpTracedRequestListener(),
         rumResourceAttributesProvider: RumResourceAttributesProvider =
-            NoOpRumResourceAttributesProvider()
+            NoOpRumResourceAttributesProvider(),
+        @FloatRange(from = 0.0, to = 100.0) traceSamplingRate: Float = DEFAULT_TRACE_SAMPLING_RATE
     ) : this(
         tracedHosts = emptyList(),
         tracedRequestListener = tracedRequestListener,
         firstPartyHostDetector = CoreFeature.firstPartyHostDetector,
         rumResourceAttributesProvider = rumResourceAttributesProvider,
+        traceSampler = RateBasedSampler(traceSamplingRate / 100),
         localTracerFactory = { AndroidTracer.Builder().build() }
     )
 
@@ -169,7 +186,6 @@ internal constructor(
         throwable: Throwable?
     ) {
         super.onRequestIntercepted(request, span, response, throwable)
-
         if (RumFeature.isInitialized()) {
             if (response != null) {
                 handleResponse(request, response, span)

dd-sdk-android/src/main/kotlin/com/datadog/android/rum/RumInterceptor.kt

@@ -6,6 +6,7 @@
 
 package com.datadog.android.rum
 
+import androidx.annotation.FloatRange
 import com.datadog.android.DatadogInterceptor
 import com.datadog.android.core.configuration.Configuration
 import com.datadog.android.rum.tracking.ViewTrackingStrategy
@@ -36,16 +37,22 @@ import okhttp3.Request
  * Requests made to a URL with any one of these hosts (or any subdomain) will:
  * - be considered a first party RUM Resource and categorised as such in your RUM dashboard;
  * - be wrapped in a Span and have trace id injected to get a full flame-graph in APM.
- * If no host provided the interceptor won't trace any OkHttp [Request], nor propagate tracing
+ * If no host provided (via this argument or global configuration [Configuration.Builder.setFirstPartyHosts])
+ * the interceptor won't trace any OkHttp [Request], nor propagate tracing
  * information to the backend, but RUM Resource events will still be sent for each request.
  * @param rumResourceAttributesProvider which listens on the intercepted [okhttp3.Request]
  * and offers the possibility to add custom attributes to the RUM resource events.
+ * @param traceSamplingRate the sampling rate for APM traces created for auto-instrumented
+ * requests. It must be a value between `0.0` and `100.0`. A value of `0.0` means no trace will
+ * be kept, `100.0` means all traces will be kept (default value is `20.0`).
  */
 class RumInterceptor(
     firstPartyHosts: List<String> = emptyList(),
     rumResourceAttributesProvider: RumResourceAttributesProvider =
-        NoOpRumResourceAttributesProvider()
+        NoOpRumResourceAttributesProvider(),
+    @FloatRange(from = 0.0, to = 100.0) traceSamplingRate: Float = DEFAULT_TRACE_SAMPLING_RATE
 ) : DatadogInterceptor(
     firstPartyHosts,
-    rumResourceAttributesProvider = rumResourceAttributesProvider
+    rumResourceAttributesProvider = rumResourceAttributesProvider,
+    traceSamplingRate = traceSamplingRate
 )

dd-sdk-android/src/main/kotlin/com/datadog/android/tracing/TracedRequestListener.kt

@@ -20,7 +20,8 @@ interface TracedRequestListener {
 
     /**
      * Notifies that a span was automatically created around an OkHttp [Request].
-     * You can update the given [Span] (e.g.: add custom tags / baggage items) before it is persisted.
+     * You can update the given [Span] (e.g.: add custom tags / baggage items) before it
+     * is persisted. Won't be called if [Request] wasn't sampled.
      * @param request the intercepted [Request]
      * @param span the [Span] created around the intercepted [Request]
      * @param response the [Request] response in case of any