Add benchmark profiling tool and update docs

Signed-off-by: AkramBitar <akram@il.ibm.com>

Author: AkramBitar

docs/drivers/benchmark/core/dlognogh/validator_transfer_profile.md

@@ -179,9 +179,13 @@ func TestFetchIdentityFromCacheNilEntry(t *testing.T) {
 		}, nil
 	}, 10, nil, NewMetrics(&disabled.Provider{}))
 
-	// Send nil to cache to test nil handling
+	// Pre-populate the cache with nil before calling Identity()
+	// Since cache is buffered, this completes immediately
 	c.cache <- nil
 
+	// Small delay to ensure the nil is in the buffer before Identity() reads
+	time.Sleep(10 * time.Millisecond)
+
 	identityDescriptor, err := c.Identity(context.Background(), nil)
 	require.NoError(t, err)
 	assert.Eventually(t, func() bool {

token/services/identity/idemix/cache/cache_test.go

@@ -0,0 +1,6 @@
+# Profiler output files (generated by profile.sh)
+*_profile.md
+
+# Exclude the README files (they should be committed)
+!README.md
+!tracer/README.md

tools/profiler/.gitignore

@@ -0,0 +1,184 @@
+# Test & Benchmark Profiler
+
+Automatic hierarchical call tracing and performance profiling for Go tests and benchmarks in the Token SDK.
+
+## Quick Start
+
+```bash
+cd tools/profiler
+./profile.sh BenchmarkValidatorTransfer
+```
+
+## What It Does
+
+1. Copies your repo to `/tmp/profiler-<PID>` (your files are never touched)
+2. Finds your test/benchmark in `token/` directory
+3. Instruments all Go packages in `token/`
+4. Runs with profiling
+5. Saves results to current directory
+6. Cleans up automatically
+
+**Safety:** All work happens in `/tmp`. Your repository is never modified.
+
+## Example Output
+
+```
+## Call Hierarchy
+
+└── >>> (*Validator).VerifyTransfer [2.5s, 100.00%]
+    ├── >>> (*Validator).verifyInputs [1.8s, 72.00%]
+    │   └── >>> (*Verifier).Verify x5 [1.5s, 60.00%]
+    └── (*Validator).verifyOutputs [0.7s, 28.00%]
+
+## Top 20 Functions by Time
+
+*Note: These functions are marked with `>>>` in the call tree above*
+
+| Function | Total Time | % of Root |
+|----------|------------|-----------|
+| (*Validator).VerifyTransfer | 2.5s | 100.00% |
+| (*Validator).verifyInputs | 1.8s | 72.00% |
+| (*Verifier).Verify | 1.5s | 60.00% |
+```
+
+**Reading the output:**
+- `>>>` marks the top 20 functions by time
+- Times are **cumulative** (include all child functions)
+- `x5` means called 5 times (total time shown)
+- Percentages relative to root function
+
+## Options
+
+```bash
+./profile.sh <test_or_benchmark_name> [options]
+
+Options:
+  -d, --display <mode>      Display: both, time, percent (default: both)
+  -f, --root-function <name> Start from this function (show subtree)
+  -m, --min-percent <n>     Hide functions below this % (default: 0)
+  -h, --help                Show help
+```
+
+**Examples:**
+```bash
+# Show only percentages
+./profile.sh BenchmarkValidatorTransfer -d percent
+
+# Profile a subtree
+./profile.sh BenchmarkValidatorTransfer -f VerifyTransfer
+
+# Hide functions using less than 1%
+./profile.sh BenchmarkValidatorTransfer -m 1.0
+
+# Profile a test
+./profile.sh TestValidatorTransfer
+```
+
+## Scope
+
+**Searches for tests/benchmarks in:**
+- `token/` directory and all subdirectories
+
+**Instruments:**
+- All Go packages in `token/` directory
+
+**Output:**
+- Saved to current directory as `<TestName>_profile.md`
+
+## Manual Instrumentation
+
+The `profile.sh` script automatically instruments your code. However, you can also manually instrument code for profiling.
+
+### In Benchmarks
+
+```go
+import "github.com/hyperledger-labs/fabric-token-sdk/tools/profiler/tracer"
+
+func BenchmarkValidatorTransfer(b *testing.B) {
+    // Enable tracer
+    tracer.Enable()
+    defer tracer.Disable()
+    
+    // Setup code (not profiled)
+    validator := setupValidator()
+    request := generateRequest()
+    
+    b.ResetTimer()
+    for i := 0; i < b.N; i++ {
+        // This will be profiled if functions have tracer.Enter() calls
+        err := validator.VerifyTransfer(request)
+        if err != nil {
+            b.Fatal(err)
+        }
+    }
+    b.StopTimer()
+    
+    // Print profile
+    tracer.PrintWithOptions(tracer.PrintOptions{
+        RootFunction:   "VerifyTransfer",
+        ShowPercent:    true,
+        ShowAbsolute:   true,
+        AggregateLoops: true,
+    })
+}
+
+// Each function you want to profile needs this:
+func (v *Validator) VerifyTransfer(req *Request) error {
+    defer tracer.Enter("(*Validator).VerifyTransfer")()
+    // ... function body ...
+}
+```
+
+### In Tests
+
+```go
+func TestValidatorTransfer(t *testing.T) {
+    // Enable tracer
+    tracer.Enable()
+    defer tracer.Disable()
+    
+    // Run test
+    validator := setupValidator()
+    request := generateRequest()
+    
+    err := validator.VerifyTransfer(request)
+    require.NoError(t, err)
+    
+    // Print profile
+    tracer.PrintWithOptions(tracer.PrintOptions{
+        RootFunction:   "VerifyTransfer",
+        ShowPercent:    true,
+        ShowAbsolute:   true,
+        AggregateLoops: true,
+    })
+}
+```
+
+**Note:** Manual instrumentation requires adding `defer tracer.Enter("FunctionName")()` to every function you want to profile. The `profile.sh` script does this automatically by:
+1. Copying your code to a temporary directory
+2. Running `auto-instrument.go` to add tracer calls
+3. Running the test/benchmark
+4. Cleaning up
+
+For most use cases, use `profile.sh` instead of manual instrumentation.
+
+## Files
+
+- `profile.sh` - Automated profiling script
+- `auto-instrument.go` - Adds tracer hooks to Go files
+- `inject-tracer.go` - Injects tracer into test/benchmark
+- `tracer/` - Runtime tracing library
+
+## Troubleshooting
+
+**Can't find test/benchmark:**
+- Check spelling
+- Ensure it's in `token/` directory
+
+**Empty output file:**
+- Check if test/benchmark runs successfully
+- Look for compilation errors in script output
+
+**Times don't add up:**
+- Times are cumulative (include children)
+- Use percentages to see relative contributions