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feat(agent): ClassFile API backend ordinary args + AnyType[] + review-nit cleanup #948

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Merged
jbachorik merged 5 commits into from
Sep 1, 2026
Merged

feat(agent): ClassFile API backend ordinary args + AnyType[] + review-nit cleanup #948

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872a865
chore: ignore OS/editor/tool noise and integration-test thread dumps
jbachorik Aug 23, 2026
05cb097
feat(agent): support ordinary method args + AnyType[] in ClassFile AP…
jbachorik Aug 23, 2026
058fc19
refactor(agent): fold ClassFilter cache null-guard into ci null-check
jbachorik Aug 23, 2026
23767f5
test(integration): reference captured probe params in ClassFileApi sm…
jbachorik Aug 23, 2026
8f91204
docs: add ClassFile API backend remaining-gaps plan
jbachorik Aug 23, 2026
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7 changes: 7 additions & 0 deletions .gitignore
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Original file line number Diff line number Diff line change
Expand Up @@ -47,3 +47,10 @@ gradle-wrapper.properties
/.java.versions
compile.log
.worktrees/

# OS / editor / tool noise
.DS_Store
.cachebro/
gradle/gradle-daemon-jvm.properties
# JVM thread-dump artifacts from stalled integration tests
javacore.*.txt
14 changes: 6 additions & 8 deletions btrace-agent/src/main/java/io/btrace/instr/ClassFilter.java
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Original file line number Diff line number Diff line change
Expand Up @@ -174,15 +174,13 @@ public static boolean isSubTypeOf(String typeA, ClassLoader loader, String... ty
return true;
}
ClassCache cache = ClassCache.getInstance();
if (cache == null) {
// Reentrant class loading can observe the holder before INSTANCE assignment completes.
return false;
}
ClassInfo ci = cache.get(loader, typeA);
// ClassCache.getInstance() uses the holder idiom (static final in a nested class), so
// cache is never null under normal JLS class-initialization semantics. Fold the
// defensive cache-unavailable case together with the not-cached case: either way we
// cannot resolve the supertypes, so conservatively report "not a subtype" and let the
// caller fall back to a no-op transform or a different check.
ClassInfo ci = cache != null ? cache.get(loader, typeA) : null;
if (ci == null) {
// ClassInfo not present in the cache (or cache temporarily unavailable due to a
// classloader-init race). Conservatively report "not a subtype" rather than NPE;
// the caller can fall back to a no-op transform or a different check.
return false;
}
Collection<ClassInfo> sTypesInfo = ci.getSupertypes(false);
Expand Down
164 changes: 156 additions & 8 deletions btrace-agent/src/main/java24/io/btrace/instr/ClassFileApiBackend.java
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Original file line number Diff line number Diff line change
Expand Up @@ -113,6 +113,7 @@ public final class ClassFileApiBackend implements InstrumentationBackend {
ClassDesc.of("java.lang.String"));

private static final ClassDesc INDY_DISPATCHER = ClassDesc.of("io.btrace.runtime.IndyDispatcher");
private static final ClassDesc CD_OBJECT = ClassDesc.of("java.lang.Object");
private static final ClassDesc CD_METHOD_TRACKER =
ClassDesc.ofInternalName("io/btrace/instr/MethodTracker");
private static final MethodTypeDesc HIT_DESC = MethodTypeDesc.ofDescriptor("(I)Z");
Expand Down Expand Up @@ -705,6 +706,8 @@ private static CodeTransform buildCodeTransform(
Map<Label, List<String>> catchHandlerTypes,
boolean[] anyMatch) {

Type[] methodArgTypes = Type.getArgumentTypes(methodDesc);

// hasDurationReturn: RETURN probes need duration → compute nanoTime on each RETURN path
boolean hasDurationReturn =
returnHandlers.stream().anyMatch(ph -> ph.om.getDurationParameter() != -1);
Expand Down Expand Up @@ -819,12 +822,12 @@ public void accept(CodeBuilder cb, CodeElement ce) {
Label skipLabel = cb.newLabel();
cb.iload(sHitSlot[0]);
cb.ifeq(skipLabel);
emitProbeCall(cb, ph, javaClassName, methodName, isStatic, true, -1, TypeKind.VOID, -1);
emitProbeCall(cb, ph, javaClassName, methodName, isStatic, true, methodArgTypes, -1, TypeKind.VOID, -1);
cb.labelBinding(skipLabel);
} else {
emitWithSamplingGuard(
cb, ph, samplingMethodId,
() -> emitProbeCall(cb, ph, javaClassName, methodName, isStatic, true, -1, TypeKind.VOID, -1));
() -> emitProbeCall(cb, ph, javaClassName, methodName, isStatic, true, methodArgTypes, -1, TypeKind.VOID, -1));
}
}
if (isSynchronizedMethod) {
Expand Down Expand Up @@ -893,8 +896,8 @@ public void accept(CodeBuilder cb, CodeElement ce) {
emitWithSamplingGuard(
cb, ph, samplingMethodId,
() -> emitProbeCall(
cb, ph, javaClassName, methodName, isStatic, false,
fLocalRetValSlot, methodReturnType, fReturnKind, fLocalDurationSlot, null));
cb, ph, javaClassName, methodName, isStatic, false, methodArgTypes,
fLocalRetValSlot, methodReturnType, fReturnKind, fLocalDurationSlot));
}
}
if (adaptiveReturnHandlers != null) {
Expand All @@ -905,8 +908,8 @@ public void accept(CodeBuilder cb, CodeElement ce) {
cb.invokestatic(CD_METHOD_TRACKER, "updateEndTs", UPDATE_END_TS_DESC);
for (ProbeHandler ph : adaptiveReturnHandlers) {
emitProbeCall(
cb, ph, javaClassName, methodName, isStatic, false,
fLocalRetValSlot, methodReturnType, fReturnKind, fLocalDurationSlot, null);
cb, ph, javaClassName, methodName, isStatic, false, methodArgTypes,
fLocalRetValSlot, methodReturnType, fReturnKind, fLocalDurationSlot);
}
cb.labelBinding(skipAdaptive);
}
Expand Down Expand Up @@ -2655,6 +2658,7 @@ private static boolean emitNewArrayProbe(
methodName,
isStatic,
false,
null,
ctx.returnSlot,
ctx.arrayType,
TypeKind.REFERENCE,
Expand All @@ -2675,8 +2679,10 @@ private static boolean canEmitCallProbe(ProbeHandler ph, InvokeInstruction ii, C
String rawDesc =
om.getTargetDescriptor().replace(Constants.ANYTYPE_DESC, Constants.OBJECT_DESC);
Type[] handlerArgTypes = Type.getArgumentTypes(rawDesc);
// Original (pre-replacement) descriptor: needed to recognise AnyType[] aggregate params,
// which the replaced descriptor flattens to Object[].
Type[] originalHandlerArgTypes = Type.getArgumentTypes(om.getTargetDescriptor());
Type[] callArgTypes = Type.getArgumentTypes(ii.type().stringValue());
boolean staticCall = ii.opcode() == Opcode.INVOKESTATIC;
Type ownerType = Type.getObjectType(ii.owner().asInternalName());
for (int i = 0; i < handlerArgTypes.length; i++) {
if (i == om.getSelfParameter()
Expand Down Expand Up @@ -2725,6 +2731,11 @@ private static boolean canEmitCallProbe(ProbeHandler ph, InvokeInstruction ii, C
}
continue;
}
// AnyType[] aggregate: packages all call args into Object[] regardless of their
// individual types (mirrors ASM MethodCallInstrumentor + AnyTypeArgProvider).
if (TypeUtils.isAnyTypeArray(originalHandlerArgTypes[i])) {
continue;
}
int callArgIndex = callArgumentIndex(om, i);
if (callArgIndex < 0 || callArgIndex >= callArgTypes.length) {
return false;
Expand Down Expand Up @@ -3300,6 +3311,7 @@ private static boolean emitProbeCall(
methodName,
isStatic,
isEntry,
null,
retValSlot,
returnType,
returnKind,
Expand All @@ -3315,13 +3327,85 @@ private static boolean emitProbeCall(
null);
}

// ENTRY convenience: enclosing-method args available, no return value, no call context.
private static boolean emitProbeCall(
CodeBuilder cb,
ProbeHandler ph,
String javaClassName,
String methodName,
boolean isStatic,
boolean isEntry,
Type[] methodArgTypes,
int retValSlot,
TypeKind returnKind,
int durationSlot) {
return emitProbeCall(
cb,
ph,
javaClassName,
methodName,
isStatic,
isEntry,
methodArgTypes,
retValSlot,
null,
returnKind,
durationSlot,
null,
-1,
null,
null,
null,
null,
null,
null,
null);
}

// RETURN convenience: enclosing-method args available, with return value + duration slots.
private static boolean emitProbeCall(
CodeBuilder cb,
ProbeHandler ph,
String javaClassName,
String methodName,
boolean isStatic,
boolean isEntry,
Type[] methodArgTypes,
int retValSlot,
Type returnType,
TypeKind returnKind,
int durationSlot) {
return emitProbeCall(
cb,
ph,
javaClassName,
methodName,
isStatic,
isEntry,
methodArgTypes,
retValSlot,
returnType,
returnKind,
durationSlot,
null,
-1,
null,
null,
null,
null,
null,
null,
null);
}

private static boolean emitProbeCall(
CodeBuilder cb,
ProbeHandler ph,
String javaClassName,
String methodName,
boolean isStatic,
boolean isEntry,
Type[] methodArgTypes,
int retValSlot,
Type returnType,
TypeKind returnKind,
Expand All @@ -3340,6 +3424,10 @@ private static boolean emitProbeCall(
String rawDesc =
om.getTargetDescriptor().replace(Constants.ANYTYPE_DESC, Constants.OBJECT_DESC);
Type[] argTypes = Type.getArgumentTypes(rawDesc);
// Original (pre-replacement) handler arg types: needed to detect AnyType[] aggregate
// params, which the replaced descriptor flattens to Object[]. ENTRY/RETURN ordinary method
// args and CALL ordinary call args are only loaded when methodArgTypes / callContext is set.
Type[] originalArgTypes = Type.getArgumentTypes(om.getTargetDescriptor());

// Pre-validate: every argument must be satisfiable before we push anything onto the stack.
// An early return mid-loop would leave orphaned stack values, causing a VerifyError.
Expand Down Expand Up @@ -3373,7 +3461,15 @@ private static boolean emitProbeCall(
|| (typeCheckContext != null && ordinaryArgumentIndex(om, i) == 0)
|| (newArrayContext != null && ordinaryArgumentIndex(om, i) == 0)
|| (newArrayContext != null && ordinaryArgumentIndex(om, i) == 1)
|| (callArgIndex >= 0 && callArgIndex < callContext.argumentTypes.length);
|| (callArgIndex >= 0 && callArgIndex < callContext.argumentTypes.length)
// ENTRY/RETURN ordinary enclosing-method args (typed or AnyType[] aggregate).
|| (methodArgTypes != null
&& TypeUtils.isAnyTypeArray(originalArgTypes[i]))
|| (methodArgTypes != null
&& ordinaryArgumentIndex(om, i) >= 0
&& ordinaryArgumentIndex(om, i) < methodArgTypes.length)
// CALL AnyType[] aggregate packages all call args into Object[].
|| (callContext != null && TypeUtils.isAnyTypeArray(originalArgTypes[i]));
if (!satisfiable) {
log.debug(
"ClassFileApiBackend: skipping handler {}.{} — arg {} cannot be satisfied",
Expand Down Expand Up @@ -3467,6 +3563,17 @@ && typeKind(argTypes[i]) == TypeKind.REFERENCE) {
cb.ldc(newArrayContext.extName);
} else if (newArrayContext != null && ordinaryArgumentIndex(om, i) == 1) {
cb.ldc(newArrayContext.dims);
} else if (TypeUtils.isAnyTypeArray(originalArgTypes[i])
&& (methodArgTypes != null || callContext != null)) {
// AnyType[] aggregate: package all enclosing-method args (ENTRY/RETURN) or all call
// args (CALL) into an Object[], boxing primitives. Mirrors ASM AnyTypeArgProvider.
emitAnyTypeArray(cb, isStatic, methodArgTypes, callContext);
} else if (methodArgTypes != null) {
// Typed ordinary enclosing-method argument (ENTRY/RETURN). Loaded from its fixed
// method-local slot; no boxing — the handler type must match the method arg type
// (validated upstream), matching the existing CALL typed-arg path.
int ordIdx = ordinaryArgumentIndex(om, i);
cb.loadLocal(typeKind(methodArgTypes[ordIdx]), methodArgSlot(isStatic, methodArgTypes, ordIdx));
} else if (callContext != null) {
int callArgIndex = callArgumentIndex(om, i);
cb.loadLocal(
Expand All @@ -3490,6 +3597,47 @@ && typeKind(argTypes[i]) == TypeKind.REFERENCE) {
return true;
}

// Fixed local-variable slot for the ordinary enclosing-method argument at
// ordinaryIndex (0-based). `this` occupies slot 0 for instance methods.
private static int methodArgSlot(boolean isStatic, Type[] methodArgTypes, int ordinaryIndex) {
int slot = isStatic ? 0 : 1;
for (int j = 0; j < ordinaryIndex; j++) {
slot += methodArgTypes[j].getSize();
}
return slot;
}

// Package all enclosing-method args (ENTRY/RETURN, methodArgTypes != null) or all call args
// (CALL, callContext != null) into an Object[], boxing primitives. Mirrors ASM
// MethodInstrumentor.AnyTypeArgProvider.doProvide.
private static void emitAnyTypeArray(
CodeBuilder cb, boolean isStatic, Type[] methodArgTypes, CallContext callContext) {
boolean useMethod = methodArgTypes != null;
Type[] srcTypes = useMethod ? methodArgTypes : callContext.argumentTypes;
cb.ldc(srcTypes.length);
cb.anewarray(CD_OBJECT);
for (int j = 0; j < srcTypes.length; j++) {
TypeKind tk = typeKind(srcTypes[j]);
int slot = useMethod ? methodArgSlot(isStatic, methodArgTypes, j) : callContext.argumentSlots[j];
cb.dup();
cb.ldc(j);
cb.loadLocal(tk, slot);
boxIfPrimitive(cb, srcTypes[j], tk);
cb.arrayStore(TypeKind.REFERENCE);
}
}

// Box a primitive on the stack to its wrapper; no-op for references. The JVMS verifier
// collapses byte/short/char/boolean to int, so valueOf(B/S/C/Z) accepts the int on stack.
private static void boxIfPrimitive(CodeBuilder cb, Type t, TypeKind tk) {
if (tk == TypeKind.INT
|| tk == TypeKind.LONG
|| tk == TypeKind.FLOAT
|| tk == TypeKind.DOUBLE) {
boxPrimitiveReturn(cb, t, tk);
}
}

private static void boxPrimitiveReturn(CodeBuilder cb, Type returnType, TypeKind returnKind) {
String primitiveDesc = returnType != null ? returnType.getDescriptor() : primitiveDesc(returnKind);
String wrapperInternalName = wrapperInternalName(primitiveDesc);
Expand Down
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