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| 1 | +package datadog.trace.bootstrap.instrumentation.ffm; |
| 2 | + |
| 3 | +import datadog.context.ContextScope; |
| 4 | +import datadog.trace.api.InstrumenterConfig; |
| 5 | +import datadog.trace.bootstrap.instrumentation.api.AgentSpan; |
| 6 | +import datadog.trace.bootstrap.instrumentation.api.AgentTracer; |
| 7 | +import datadog.trace.bootstrap.instrumentation.api.UTF8BytesString; |
| 8 | +import datadog.trace.bootstrap.instrumentation.decorator.BaseDecorator; |
| 9 | +import java.lang.invoke.MethodHandle; |
| 10 | +import java.lang.invoke.MethodHandles; |
| 11 | +import java.lang.invoke.MethodType; |
| 12 | +import java.util.Set; |
| 13 | +import org.slf4j.Logger; |
| 14 | +import org.slf4j.LoggerFactory; |
| 15 | + |
| 16 | +public final class FFMNativeMethodDecorator extends BaseDecorator { |
| 17 | + private static final Logger LOGGER = LoggerFactory.getLogger(FFMNativeMethodDecorator.class); |
| 18 | + private static final CharSequence TRACE_FFM = UTF8BytesString.create("trace-ffm"); |
| 19 | + private static final CharSequence OPERATION_NAME = UTF8BytesString.create("trace.native"); |
| 20 | + |
| 21 | + private static final MethodHandle START_SPAN_MH = |
| 22 | + safeFindStatic( |
| 23 | + "startSpan", |
| 24 | + MethodType.methodType(ContextScope.class, CharSequence.class, boolean.class)); |
| 25 | + private static final MethodHandle END_SPAN_MH = |
| 26 | + safeFindStatic( |
| 27 | + "endSpan", |
| 28 | + MethodType.methodType(Object.class, Throwable.class, ContextScope.class, Object.class)); |
| 29 | + |
| 30 | + public static final FFMNativeMethodDecorator DECORATE = new FFMNativeMethodDecorator(); |
| 31 | + |
| 32 | + private static MethodHandle safeFindStatic(String name, MethodType methodType) { |
| 33 | + try { |
| 34 | + return MethodHandles.lookup().findStatic(FFMNativeMethodDecorator.class, name, methodType); |
| 35 | + } catch (Throwable t) { |
| 36 | + LOGGER.debug("Cannot find method {} in NativeMethodHandleWrapper", name, t); |
| 37 | + return null; |
| 38 | + } |
| 39 | + } |
| 40 | + |
| 41 | + public static MethodHandle wrap( |
| 42 | + final MethodHandle original, final String libraryName, final String methodName) { |
| 43 | + if (START_SPAN_MH == null || END_SPAN_MH == null) { |
| 44 | + return original; |
| 45 | + } |
| 46 | + try { |
| 47 | + MethodType originalType = original.type(); |
| 48 | + boolean isVoid = originalType.returnType() == void.class; |
| 49 | + |
| 50 | + // We need the ContextScope to be visible to the finally block. |
| 51 | + // Easiest way is to artificially prepend it to the target signature. |
| 52 | + // The added parameter is ignored by the original handle. |
| 53 | + // originalWithScope: (ContextScope, args...) -> R |
| 54 | + MethodHandle originalWithScope = MethodHandles.dropArguments(original, 0, ContextScope.class); |
| 55 | + |
| 56 | + /* |
| 57 | + * Build the cleanup handle used by MethodHandles.tryFinally. |
| 58 | + * |
| 59 | + * tryFinally has a strict calling convention: |
| 60 | + * - void target -> cleanup(Throwable, ContextScope, args...) |
| 61 | + * - non-void -> cleanup(Throwable, R, ContextScope, args...) |
| 62 | + * |
| 63 | + * END_SPAN_MH is (Throwable, ContextScope, Object) -> Object, |
| 64 | + * so we need to reshape it to match what tryFinally expects. |
| 65 | + */ |
| 66 | + MethodHandle cleanup; |
| 67 | + |
| 68 | + if (isVoid) { |
| 69 | + // No return value: bind `null` as the result argument. |
| 70 | + MethodHandle endWithNull = MethodHandles.insertArguments(END_SPAN_MH, 2, (Object) null); |
| 71 | + |
| 72 | + // Make it accept the original arguments even though they are unused. |
| 73 | + MethodHandle endDropped = |
| 74 | + MethodHandles.dropArguments(endWithNull, 2, originalType.parameterList()); |
| 75 | + |
| 76 | + // tryFinally requires void return for void targets. |
| 77 | + cleanup = endDropped.asType(endDropped.type().changeReturnType(void.class)); |
| 78 | + |
| 79 | + } else { |
| 80 | + /* |
| 81 | + * Non-void case: |
| 82 | + * tryFinally will call cleanup as: |
| 83 | + * (Throwable, returnValue, ContextScope, args...) |
| 84 | + * |
| 85 | + * END_SPAN_MH expects: |
| 86 | + * (Throwable, ContextScope, result) |
| 87 | + * |
| 88 | + * So we first permute parameters to swap returnValue and ContextScope. |
| 89 | + */ |
| 90 | + MethodHandle endPermuted = |
| 91 | + MethodHandles.permuteArguments( |
| 92 | + END_SPAN_MH, |
| 93 | + MethodType.methodType( |
| 94 | + Object.class, Throwable.class, Object.class, ContextScope.class), |
| 95 | + 0, |
| 96 | + 2, |
| 97 | + 1); |
| 98 | + |
| 99 | + // Accept original arguments (unused) after the required ones. |
| 100 | + MethodHandle endDropped = |
| 101 | + MethodHandles.dropArguments(endPermuted, 3, originalType.parameterList()); |
| 102 | + |
| 103 | + // Adapt return and result parameter types to match the original signature. |
| 104 | + MethodType cleanupType = |
| 105 | + endDropped |
| 106 | + .type() |
| 107 | + .changeParameterType(1, originalType.returnType()) |
| 108 | + .changeReturnType(originalType.returnType()); |
| 109 | + |
| 110 | + cleanup = endDropped.asType(cleanupType); |
| 111 | + } |
| 112 | + |
| 113 | + // Wrap the original in try/finally semantics. |
| 114 | + // Resulting handle: |
| 115 | + // (ContextScope, args...) -> R |
| 116 | + MethodHandle withFinally = MethodHandles.tryFinally(originalWithScope, cleanup); |
| 117 | + |
| 118 | + // Precompute span metadata so we don't redo the lookup per invocation. |
| 119 | + final CharSequence resourceName = resourceNameFor(libraryName, methodName); |
| 120 | + final boolean methodMeasured = isMethodMeasured(libraryName, methodName); |
| 121 | + |
| 122 | + // Bind both arguments to startSpan. |
| 123 | + // After binding: () -> ContextScope |
| 124 | + MethodHandle boundStart = |
| 125 | + MethodHandles.insertArguments(START_SPAN_MH, 0, resourceName, methodMeasured); |
| 126 | + |
| 127 | + // Make it look like it takes the same arguments as the original, |
| 128 | + // even though they are ignored. |
| 129 | + // (args...) -> ContextScope |
| 130 | + MethodHandle startCombiner = |
| 131 | + MethodHandles.dropArguments(boundStart, 0, originalType.parameterList()); |
| 132 | + |
| 133 | + /* |
| 134 | + * foldArguments wires it all together: |
| 135 | + * |
| 136 | + * scope = startCombiner(args...) |
| 137 | + * return withFinally(scope, args...) |
| 138 | + * |
| 139 | + * Final shape matches the original: |
| 140 | + * (args...) -> R |
| 141 | + */ |
| 142 | + return MethodHandles.foldArguments(withFinally, startCombiner); |
| 143 | + |
| 144 | + } catch (Throwable t) { |
| 145 | + LOGGER.debug( |
| 146 | + "Cannot wrap method handle for library {} and method {}", libraryName, methodName, t); |
| 147 | + return original; |
| 148 | + } |
| 149 | + } |
| 150 | + |
| 151 | + @SuppressWarnings("unused") |
| 152 | + public static ContextScope startSpan(CharSequence resourceName, boolean methodMeasured) { |
| 153 | + AgentSpan span = AgentTracer.startSpan(TRACE_FFM.toString(), OPERATION_NAME); |
| 154 | + DECORATE.afterStart(span); |
| 155 | + span.setResourceName(resourceName); |
| 156 | + return AgentTracer.activateSpan(span); |
| 157 | + } |
| 158 | + |
| 159 | + @SuppressWarnings("unused") |
| 160 | + public static Object endSpan(Throwable t, ContextScope scope, Object result) { |
| 161 | + try { |
| 162 | + if (scope != null) { |
| 163 | + final AgentSpan span = AgentSpan.fromContext(scope.context()); |
| 164 | + scope.close(); |
| 165 | + |
| 166 | + if (span != null) { |
| 167 | + if (t != null) { |
| 168 | + DECORATE.onError(span, t); |
| 169 | + span.addThrowable(t); |
| 170 | + } |
| 171 | + |
| 172 | + span.finish(); |
| 173 | + } |
| 174 | + } |
| 175 | + } catch (Throwable ignored) { |
| 176 | + |
| 177 | + } |
| 178 | + return result; |
| 179 | + } |
| 180 | + |
| 181 | + public static boolean isMethodTraced(final String library, final String method) { |
| 182 | + return matches(InstrumenterConfig.get().getTraceNativeMethods().get(library), method); |
| 183 | + } |
| 184 | + |
| 185 | + public static boolean isMethodMeasured(final String library, final String method) { |
| 186 | + return matches(InstrumenterConfig.get().getMeasureMethods().get(library), method); |
| 187 | + } |
| 188 | + |
| 189 | + public static CharSequence resourceNameFor(final String library, final String method) { |
| 190 | + if (library == null || library.isEmpty()) { |
| 191 | + return UTF8BytesString.create(method); |
| 192 | + } |
| 193 | + return UTF8BytesString.create(library + "." + method); |
| 194 | + } |
| 195 | + |
| 196 | + private static boolean matches(final Set<String> allows, final String method) { |
| 197 | + if (allows == null) { |
| 198 | + return false; |
| 199 | + } |
| 200 | + return allows.contains(method) || allows.contains("*"); |
| 201 | + } |
| 202 | + |
| 203 | + @Override |
| 204 | + protected String[] instrumentationNames() { |
| 205 | + return new String[] {TRACE_FFM.toString()}; |
| 206 | + } |
| 207 | + |
| 208 | + @Override |
| 209 | + protected CharSequence spanType() { |
| 210 | + return null; |
| 211 | + } |
| 212 | + |
| 213 | + @Override |
| 214 | + protected CharSequence component() { |
| 215 | + return TRACE_FFM; |
| 216 | + } |
| 217 | +} |
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