squashing & signing (#8589)

This change introduces TagMap as replacement for HashMap when working with tags.
TagMap has two different implementations...
- one that extends a regular HashMap
- another that uses a different approach that allows for Entry sharing

This change currently uses the HashMap approach by default, but allows for switching to the optimized Map
via a configuration flag.

The optimized TagMap is designed to be good at operations that the tracer performs regularly but HashMap
isn't great at.  Specifically, Map-to-Map copies and storing primitives.

To get the benefit of the optimized TagMap, calling code needs to use TagMap-s for both the source and destination map.
The calling code also needs to make sure to use the bulk operations that which are the most optimized.

To take advantage of TagMap in span creation, a mechanism was introduced that allows for bypassing TagInterceptors.
Bypassing TagInterceptors is done by analyzing a TagMap that is going to be reused ahead-of-time to determine if
interception is needed.  If interception isn't needed, then SpanBuilder can use a bulk operation to update the map.

To maintain the insertion order semantics of SpanBuilder, TagMap also includes a Ledger.
A Ledger is concatenative ledger of entry modifications to a map
A Ledger is now used in place of a LinkedHashMap in SpanBuilder to provide the insertion order semantics.

Since these changes primarily serve to reduce allocation, they should the biggest gain in memory constrained environments.
In memory constrained environments, these changes yield a 10% increase in sustainable throughput with spring-petclinic.

Author: dougqh

dd-java-agent/agent-ci-visibility/src/main/java/datadog/trace/civisibility/domain/AbstractTestSession.java

@@ -73,7 +73,7 @@ public AbstractTestSession(
     AgentSpanContext traceContext =
         new TagContext(
             CIConstants.CIAPP_TEST_ORIGIN,
-            Collections.emptyMap(),
+            null,
             null,
             null,
             PrioritySampling.UNSET,

dd-java-agent/agent-ci-visibility/src/main/java/datadog/trace/civisibility/domain/TestImpl.java

@@ -46,7 +46,6 @@
 import datadog.trace.civisibility.test.ExecutionResults;
 import java.lang.reflect.Method;
 import java.util.Collection;
-import java.util.Collections;
 import java.util.concurrent.TimeUnit;
 import java.util.function.Consumer;
 import javax.annotation.Nonnull;
@@ -105,8 +104,7 @@ public TestImpl(
 
     this.context = new TestContextImpl(coverageStore);
 
-    AgentSpanContext traceContext =
-        new TagContext(CIConstants.CIAPP_TEST_ORIGIN, Collections.emptyMap());
+    AgentSpanContext traceContext = new TagContext(CIConstants.CIAPP_TEST_ORIGIN, null);
     AgentTracer.SpanBuilder spanBuilder =
         AgentTracer.get()
             .buildSpan(CI_VISIBILITY_INSTRUMENTATION_NAME, testDecorator.component() + ".test")

dd-java-agent/agent-debugger/src/test/java/com/datadog/debugger/exception/DefaultExceptionDebuggerTest.java

@@ -27,6 +27,7 @@
 import com.datadog.debugger.util.ExceptionHelper;
 import com.datadog.debugger.util.TestSnapshotListener;
 import datadog.trace.api.Config;
+import datadog.trace.api.TagMap;
 import datadog.trace.bootstrap.debugger.CapturedContext;
 import datadog.trace.bootstrap.debugger.CapturedStackFrame;
 import datadog.trace.bootstrap.debugger.MethodLocation;
@@ -41,7 +42,6 @@
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Deque;
-import java.util.HashMap;
 import java.util.HashSet;
 import java.util.List;
 import java.util.Map;
@@ -57,7 +57,7 @@ public class DefaultExceptionDebuggerTest {
   private ConfigurationUpdater configurationUpdater;
   private DefaultExceptionDebugger exceptionDebugger;
   private TestSnapshotListener listener;
-  private Map<String, Object> spanTags = new HashMap<>();
+  private TagMap spanTags = TagMap.create();
 
   @BeforeEach
   public void setUp() {

dd-java-agent/agent-iast/src/test/groovy/com/datadog/iast/sink/HstsMissingHeaderModuleTest.groovy

@@ -7,6 +7,7 @@ import com.datadog.iast.model.Vulnerability
 import com.datadog.iast.model.VulnerabilityType
 import com.datadog.iast.overhead.Operation
 import com.datadog.iast.overhead.OverheadController
+import datadog.trace.api.TagMap
 import datadog.trace.api.gateway.Flow
 import datadog.trace.api.iast.InstrumentationBridge
 import datadog.trace.api.internal.TraceSegment
@@ -45,10 +46,10 @@ class HstsMissingHeaderModuleTest extends IastModuleImplTestBase {
     final handler = new RequestEndedHandler(dependencies)
     ctx.xForwardedProto = 'https'
     ctx.contentType = "text/html"
-    span.getTags() >> [
+    span.getTags() >> TagMap.fromMap([
       'http.url': 'https://localhost/a',
       'http.status_code': 200i
-    ]
+    ])
 
     when:
     def flow = handler.apply(reqCtx, span)

dd-java-agent/agent-iast/src/test/groovy/com/datadog/iast/sink/InsecureAuthProtocolModuleTest.groovy

@@ -5,6 +5,7 @@ import com.datadog.iast.Reporter
 import com.datadog.iast.RequestEndedHandler
 import com.datadog.iast.model.Vulnerability
 import com.datadog.iast.model.VulnerabilityType
+import datadog.trace.api.TagMap
 import datadog.trace.api.gateway.Flow
 import datadog.trace.api.iast.InstrumentationBridge
 import datadog.trace.api.iast.sink.InsecureAuthProtocolModule
@@ -42,9 +43,9 @@ class InsecureAuthProtocolModuleTest extends IastModuleImplTestBase{
     given:
     final handler = new RequestEndedHandler(dependencies)
     ctx.authorization = value
-    span.getTags() >> [
+    span.getTags() >> TagMap.fromMap([
       'http.status_code': status_code
-    ]
+    ])
 
     when:
     def flow = handler.apply(reqCtx, span)

dd-java-agent/agent-iast/src/test/groovy/com/datadog/iast/sink/XContentTypeOptionsModuleTest.groovy

@@ -5,6 +5,7 @@ import com.datadog.iast.Reporter
 import com.datadog.iast.RequestEndedHandler
 import com.datadog.iast.model.Vulnerability
 import com.datadog.iast.model.VulnerabilityType
+import datadog.trace.api.TagMap
 import datadog.trace.api.gateway.Flow
 import datadog.trace.api.iast.InstrumentationBridge
 import datadog.trace.api.internal.TraceSegment
@@ -33,9 +34,9 @@ class XContentTypeOptionsModuleTest extends IastModuleImplTestBase {
     given:
     final handler = new RequestEndedHandler(dependencies)
     ctx.contentType = "text/html"
-    span.getTags() >> [
+    span.getTags() >> TagMap.fromMap([
       'http.status_code': 200i
-    ]
+    ])
 
     when:
     def flow = handler.apply(reqCtx, span)
@@ -56,10 +57,10 @@ class XContentTypeOptionsModuleTest extends IastModuleImplTestBase {
     final handler = new RequestEndedHandler(dependencies)
     ctx.xForwardedProto = 'https'
     ctx.contentType = "text/html"
-    span.getTags() >> [
+    span.getTags() >> TagMap.fromMap([
       'http.url': url,
       'http.status_code': status
-    ]
+    ])
 
     when:
     def flow = handler.apply(reqCtx, span)

dd-java-agent/appsec/src/test/groovy/com/datadog/appsec/AppSecSystemSpecification.groovy

@@ -13,6 +13,7 @@ import datadog.remoteconfig.Product
 import datadog.remoteconfig.state.ConfigKey
 import datadog.remoteconfig.state.ProductListener
 import datadog.trace.api.Config
+import datadog.trace.api.TagMap
 import datadog.trace.api.gateway.Flow
 import datadog.trace.api.gateway.IGSpanInfo
 import datadog.trace.api.gateway.RequestContext
@@ -91,7 +92,7 @@ class AppSecSystemSpecification extends DDSpecification {
     requestEndedCB.apply(requestContext, span)
 
     then:
-    1 * span.getTags() >> ['http.client_ip':'1.1.1.1']
+    1 * span.getTags() >> TagMap.fromMap(['http.client_ip':'1.1.1.1'])
     1 * subService.registerCallback(EVENTS.requestEnded(), _) >> { requestEndedCB = it[1]; null }
     1 * requestContext.getData(RequestContextSlot.APPSEC) >> appSecReqCtx
     1 * requestContext.traceSegment >> traceSegment

dd-java-agent/appsec/src/test/groovy/com/datadog/appsec/gateway/GatewayBridgeSpecification.groovy

@@ -9,6 +9,7 @@ import com.datadog.appsec.event.data.DataBundle
 import com.datadog.appsec.event.data.KnownAddresses
 import com.datadog.appsec.report.AppSecEvent
 import com.datadog.appsec.report.AppSecEventWrapper
+import datadog.trace.api.TagMap
 import datadog.trace.api.ProductTraceSource
 import datadog.trace.api.config.GeneralConfig
 import static datadog.trace.api.config.IastConfig.IAST_DEDUPLICATION_ENABLED
@@ -173,7 +174,7 @@ class GatewayBridgeSpecification extends DDSpecification {
     def flow = requestEndedCB.apply(mockCtx, spanInfo)
 
     then:
-    1 * spanInfo.getTags() >> ['http.client_ip': '1.1.1.1']
+    1 * spanInfo.getTags() >> TagMap.fromMap(['http.client_ip': '1.1.1.1'])
     1 * mockAppSecCtx.transferCollectedEvents() >> [event]
     1 * mockAppSecCtx.peerAddress >> '2001::1'
     1 * mockAppSecCtx.close()
@@ -212,7 +213,7 @@ class GatewayBridgeSpecification extends DDSpecification {
 
     then:
     1 * mockAppSecCtx.transferCollectedEvents() >> [Stub(AppSecEvent)]
-    1 * spanInfo.getTags() >> ['http.client_ip': '8.8.8.8']
+    1 * spanInfo.getTags() >> TagMap.fromMap(['http.client_ip': '8.8.8.8'])
     1 * traceSegment.setTagTop('actor.ip', '8.8.8.8')
   }
 
@@ -1008,7 +1009,7 @@ class GatewayBridgeSpecification extends DDSpecification {
       getTraceSegment() >> traceSegment
     }
     final spanInfo = Mock(AgentSpan) {
-      getTags() >> ['http.route':'/']
+      getTags() >> TagMap.fromMap(['http.route':'/'])
     }
 
     when:
@@ -1196,7 +1197,7 @@ class GatewayBridgeSpecification extends DDSpecification {
     def flow = requestEndedCB.apply(mockCtx, spanInfo)
     then:
     1 * mockAppSecCtx.transferCollectedEvents() >> []
-    1 * spanInfo.getTags() >>  ['http.route': 'route']
+    1 * spanInfo.getTags() >>  TagMap.fromMap(['http.route': 'route'])
     1 * requestSampler.preSampleRequest(_) >> true
     0 * traceSegment.setTagTop(Tags.ASM_KEEP, true)
     0 * traceSegment.setTagTop(Tags.PROPAGATED_TRACE_SOURCE, ProductTraceSource.ASM)
@@ -1214,7 +1215,7 @@ class GatewayBridgeSpecification extends DDSpecification {
     def flow = requestEndedCB.apply(mockCtx, spanInfo)
     then:
     1 * mockAppSecCtx.transferCollectedEvents() >> []
-    1 * spanInfo.getTags() >>  ['http.route': 'route']
+    1 * spanInfo.getTags() >>  TagMap.fromMap(['http.route': 'route'])
     1 * requestSampler.preSampleRequest(_) >> false
     0 * traceSegment.setTagTop(Tags.ASM_KEEP, true)
     0 * traceSegment.setTagTop(Tags.PROPAGATED_TRACE_SOURCE, ProductTraceSource.ASM)
@@ -1233,7 +1234,7 @@ class GatewayBridgeSpecification extends DDSpecification {
     def flow = requestEndedCB.apply(mockCtx, spanInfo)
     then:
     1 * mockAppSecCtx.transferCollectedEvents() >> []
-    1 * spanInfo.getTags() >>  ['http.route': 'route']
+    1 * spanInfo.getTags() >> TagMap.fromMap(['http.route': 'route'])
     1 * requestSampler.preSampleRequest(_) >> true
     1 * traceSegment.setTagTop(Tags.ASM_KEEP, true)
     1 * traceSegment.setTagTop(Tags.PROPAGATED_TRACE_SOURCE, ProductTraceSource.ASM)

dd-java-agent/instrumentation/websocket/javax-websocket-1.0/src/test/groovy/WebsocketTest.groovy

@@ -1,5 +1,6 @@
 import datadog.trace.agent.test.AgentTestRunner
 import datadog.trace.api.DDTags
+import datadog.trace.api.TagMap
 import datadog.trace.api.sampling.PrioritySampling
 import datadog.trace.bootstrap.instrumentation.api.AgentSpan
 import datadog.trace.bootstrap.instrumentation.api.InstrumentationTags
@@ -584,7 +585,7 @@ class WebsocketTest extends AgentTestRunner {
     clientHandshake.setSamplingPriority(PrioritySampling.SAMPLER_DROP) // simulate sampler drop
     def serverHandshake = createHandshakeSpan("servlet.request", url,
     new ExtractedContext(clientHandshake.context().getTraceId(), clientHandshake.context().getSpanId(), clientHandshake.context().getSamplingPriority(),
-    "test", 0, ["example_baggage": "test"], null, null, null, null, null)) // simulate server span
+    "test", 0, ["example_baggage": "test"], TagMap.EMPTY, null, null, null, null)) // simulate server span
     def session = deployEndpointAndConnect(new Endpoints.TestEndpoint(new Endpoints.FullStringHandler()),
     clientHandshake, serverHandshake, url)
 

dd-trace-api/src/main/java/datadog/trace/api/config/GeneralConfig.java

@@ -103,6 +103,7 @@ public final class GeneralConfig {
   public static final String APM_TRACING_ENABLED = "apm.tracing.enabled";
   public static final String JDK_SOCKET_ENABLED = "jdk.socket.enabled";
 
+  public static final String OPTIMIZED_MAP_ENABLED = "optimized.map.enabled";
   public static final String STACK_TRACE_LENGTH_LIMIT = "stack.trace.length.limit";
 
   public static final String SSI_INJECTION_ENABLED = "injection.enabled";