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Map OpenTelemetry VirtualField to Datadog ContextStore (#7129)
* Map virtual field usage into context store request * Use Type.getInternalName to help future refactoring * Allow advanced mapping of OpenTelemetry method calls * Map OpenTelemetry VirtualField to Datadog ContextStore
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114 changes: 114 additions & 0 deletions
114
...t-otel/otel-tooling/src/main/java/datadog/opentelemetry/tooling/OtelMethodCallMapper.java
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,114 @@ | ||
| package datadog.opentelemetry.tooling; | ||
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| import static datadog.trace.bootstrap.FieldBackedContextStores.FAST_STORE_ID_LIMIT; | ||
| import static datadog.trace.bootstrap.FieldBackedContextStores.getContextStoreId; | ||
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| import datadog.trace.bootstrap.FieldBackedContextStore; | ||
| import datadog.trace.bootstrap.FieldBackedContextStores; | ||
| import net.bytebuddy.jar.asm.MethodVisitor; | ||
| import net.bytebuddy.jar.asm.Opcodes; | ||
| import net.bytebuddy.jar.asm.Type; | ||
| import net.bytebuddy.jar.asm.commons.MethodRemapper; | ||
| import net.bytebuddy.jar.asm.commons.Remapper; | ||
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| /** Maps OpenTelemetry method calls to use the Datadog equivalent API. */ | ||
| public final class OtelMethodCallMapper extends MethodRemapper { | ||
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| private static final String VIRTUAL_FIELD_CLASS = | ||
| "io/opentelemetry/javaagent/shaded/instrumentation/api/util/VirtualField"; | ||
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| private static final String FIELD_BACKED_CONTEXT_STORES_CLASS = | ||
| Type.getInternalName(FieldBackedContextStores.class); | ||
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| private static final String GET_CONTENT_STORE_METHOD = "getContextStore"; | ||
| private static final String GET_CONTENT_STORE_METHOD_DESCRIPTOR = | ||
| Type.getMethodDescriptor(Type.getType(FieldBackedContextStore.class), Type.INT_TYPE); | ||
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| private static final String FIELD_BACKED_CONTENT_STORE_DESCRIPTOR = | ||
| Type.getDescriptor(FieldBackedContextStore.class); | ||
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| private static final String FAST_CONTENT_STORE_PREFIX = "contextStore"; | ||
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| /** The last two constants pushed onto the stack. */ | ||
| private Object constant1, constant2; | ||
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| public OtelMethodCallMapper(MethodVisitor methodVisitor, Remapper remapper) { | ||
| super(methodVisitor, remapper); | ||
| } | ||
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| @Override | ||
| public void visitLdcInsn(final Object value) { | ||
| // 'first' constant gets moved over once 'second' one comes in | ||
| constant1 = constant2; | ||
| constant2 = value; | ||
| super.visitLdcInsn(value); | ||
| } | ||
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| @Override | ||
| public void visitMethodInsn( | ||
| final int opcode, | ||
| final String owner, | ||
| final String name, | ||
| final String descriptor, | ||
| final boolean isInterface) { | ||
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| if (VIRTUAL_FIELD_CLASS.equals(owner)) { | ||
| // replace VirtualField calls with their equivalent in the ContextStore API | ||
| if ("find".equals(name)) { | ||
| redirectVirtualFieldLookup(); | ||
| return; | ||
| } else if ("set".equals(name)) { | ||
| super.visitMethodInsn(Opcodes.INVOKEINTERFACE, owner, "put", descriptor, true); | ||
| return; | ||
| } else if ("get".equals(name)) { | ||
| super.visitMethodInsn(Opcodes.INVOKEINTERFACE, owner, "get", descriptor, true); | ||
| return; | ||
| } | ||
| } | ||
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| super.visitMethodInsn(opcode, owner, name, descriptor, isInterface); | ||
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| // reset constants for next method check | ||
| constant1 = null; | ||
| constant2 = null; | ||
| } | ||
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| private void redirectVirtualFieldLookup() { | ||
| // We track the last two constants pushed onto the stack to make sure they match | ||
| // the expected key and context types. Matching calls are rewritten to call the | ||
| // dynamically injected context store implementation instead. | ||
| String keyClassName = null; | ||
| String contextClassName = null; | ||
| if (constant1 instanceof Type && constant2 instanceof Type) { | ||
| keyClassName = ((Type) constant1).getClassName(); | ||
| contextClassName = ((Type) constant2).getClassName(); | ||
| } | ||
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| if (null == keyClassName || null == contextClassName) { | ||
| throw new IllegalStateException( | ||
| "Incorrect VirtualField usage detected. Type and fieldType must be class-literals. " | ||
| + "Example of correct usage: VirtualField.find(Runnable.class, RunnableContext.class)"); | ||
| } | ||
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| // discard original parameters so we can use numeric id instead | ||
| mv.visitInsn(Opcodes.POP2); | ||
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| int storeId = getContextStoreId(keyClassName, contextClassName); | ||
| // use fast direct field access for a small number of stores | ||
| if (storeId < FAST_STORE_ID_LIMIT) { | ||
| mv.visitFieldInsn( | ||
| Opcodes.GETSTATIC, | ||
| FIELD_BACKED_CONTEXT_STORES_CLASS, | ||
| FAST_CONTENT_STORE_PREFIX + storeId, | ||
| FIELD_BACKED_CONTENT_STORE_DESCRIPTOR); | ||
| } else { | ||
| mv.visitLdcInsn(storeId); | ||
| mv.visitMethodInsn( | ||
| Opcodes.INVOKESTATIC, | ||
| FIELD_BACKED_CONTEXT_STORES_CLASS, | ||
| GET_CONTENT_STORE_METHOD, | ||
| GET_CONTENT_STORE_METHOD_DESCRIPTOR, | ||
| false); | ||
| } | ||
| } | ||
| } |