Add diagnostic counters for failed stack unwinds

Author: jbachorik

.clang-format

@@ -0,0 +1,17 @@
+---
+Language: Cpp
+BasedOnStyle: LLVM
+IndentWidth: 4
+ColumnLimit: 100
+BreakBeforeBraces: Attach
+AllowShortFunctionsOnASingleLine: None
+AllowShortIfStatementsOnASingleLine: false
+AllowShortLoopsOnASingleLine: false
+AllowShortBlocksOnASingleLine: false
+AllowShortCaseLabelsOnASingleLine: false
+AllowShortNamespacesOnASingleLine: false
+AllowShortStructsOnASingleLine: false
+AllowShortEnumsOnASingleLine: false
+AllowShortLambdasOnASingleLine: false
+AllowShortCompoundStatementsOnASingleLine: false
+AllowShortAlwaysBreakType: None

.gitignore

@@ -30,3 +30,6 @@ datadog/maven/resources
 /gradle.properties
 **/hs_err*
 
+# cursor AI history
+.history
+

ddprof-lib/benchmarks/build.gradle

@@ -0,0 +1,60 @@
+plugins {
+  id 'cpp-application'
+}
+
+// this feels weird but it is the only way invoking `./gradlew :ddprof-lib:*` tasks will work
+if (rootDir.toString().endsWith("ddprof-lib/gradle")) {
+  apply from: rootProject.file('../../common.gradle')
+}
+
+application {
+  baseName = "unwind_failures_benchmark"
+  source.from file('src')
+  privateHeaders.from file('src')
+
+  targetMachines = [machines.macOS, machines.linux.x86_64]
+}
+
+// Include the main library headers
+tasks.withType(CppCompile).configureEach {
+  includes file('../src/main/cpp').toString()
+}
+
+// Add a task to run the benchmark
+tasks.register('runBenchmark', Exec) {
+  dependsOn 'assemble'
+  workingDir = buildDir
+
+  doFirst {
+    // Find the executable by looking for it in the build directory
+    def executableName = "unwind_failures_benchmark"
+    def executable = null
+
+    // Search for the executable in the build directory
+    buildDir.eachFileRecurse { file ->
+      if (file.isFile() && file.name == executableName && file.canExecute()) {
+        executable = file
+        return true // Stop searching once found
+      }
+    }
+
+    if (executable == null) {
+      throw new GradleException("Executable '${executableName}' not found in ${buildDir.absolutePath}. Make sure the build was successful.")
+    }
+
+    // Build command line with the executable path and any additional arguments
+    def cmd = [executable.absolutePath]
+
+    // Add any additional arguments passed to the Gradle task
+    if (project.hasProperty('args')) {
+      cmd.addAll(project.args.split(' '))
+    }
+
+    println "Running benchmark using executable at: ${executable.absolutePath}"
+    commandLine = cmd
+  }
+
+  doLast {
+    println "Benchmark completed."
+  }
+}

ddprof-lib/benchmarks/build_run.sh

@@ -0,0 +1,9 @@
+#!/bin/bash
+
+set -euo pipefail
+
+HERE="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+cd "${HERE}/.."
+
+# Build and run the benchmark using Gradle
+./gradlew :ddprof-lib:benchmarks:runBenchmark

ddprof-lib/benchmarks/src/benchmarkConfig.h

@@ -0,0 +1,22 @@
+#pragma once
+
+#include <string>
+#include <vector>
+
+struct BenchmarkResult {
+    std::string name;
+    long long total_time_ns;
+    int iterations;
+    double avg_time_ns;
+};
+
+struct BenchmarkConfig {
+    int warmup_iterations;
+    int measurement_iterations;
+    std::string csv_file;
+    std::string json_file;
+    bool debug;
+
+    BenchmarkConfig() : warmup_iterations(100000), measurement_iterations(1000000), debug(false) {
+    }
+};

ddprof-lib/benchmarks/src/unwindFailuresBenchmark.cpp

@@ -0,0 +1,268 @@
+#include "benchmarkConfig.h"
+#include "unwindStats.h"
+#include <chrono>
+#include <cstring>
+#include <fstream>
+#include <iostream>
+#include <random>
+#include <string>
+#include <vector>
+
+// Test data - using JVM stub function names
+const char *TEST_NAMES[] = {"Java_java_lang_String_toString", "Java_java_lang_Object_hashCode",
+                            "Java_java_lang_System_arraycopy",
+                            "Java_java_lang_Thread_currentThread", "Java_java_lang_Class_getName"};
+const int NUM_NAMES = sizeof(TEST_NAMES) / sizeof(TEST_NAMES[0]);
+
+// Global variables
+std::vector<BenchmarkResult> results;
+BenchmarkConfig config;
+
+// Pre-generated random values for benchmarking
+struct RandomValues {
+    std::vector<std::string> names;
+    std::vector<UnwindFailureKind> kinds;
+    std::vector<int> name_indices;
+
+    void generate(int count) {
+        std::mt19937 rng(42); // Fixed seed for reproducibility
+        names.resize(count);
+        kinds.resize(count);
+        name_indices.resize(count);
+
+        for (int i = 0; i < count; i++) {
+            name_indices[i] = rng() % NUM_NAMES;
+            names[i] = TEST_NAMES[name_indices[i]];
+            kinds[i] = static_cast<UnwindFailureKind>(rng() % 3);
+        }
+    }
+};
+
+RandomValues random_values;
+
+void exportResultsToCSV(const std::string &filename) {
+    std::ofstream file(filename);
+    if (!file.is_open()) {
+        std::cerr << "Failed to open file: " << filename << std::endl;
+        return;
+    }
+
+    // Write header
+    file << "Benchmark,Total Time (ns),Iterations,Average Time (ns)\n";
+
+    // Write data
+    for (const auto &result : results) {
+        file << result.name << "," << result.total_time_ns << "," << result.iterations << ","
+             << result.avg_time_ns << "\n";
+    }
+
+    file.close();
+    std::cout << "Results exported to CSV: " << filename << std::endl;
+}
+
+void exportResultsToJSON(const std::string &filename) {
+    std::ofstream file(filename);
+    if (!file.is_open()) {
+        std::cerr << "Failed to open file: " << filename << std::endl;
+        return;
+    }
+
+    file << "{\n  \"benchmarks\": [\n";
+    for (size_t i = 0; i < results.size(); ++i) {
+        const auto &result = results[i];
+        file << "    {\n"
+             << "      \"name\": \"" << result.name << "\",\n"
+             << "      \"total_time_ns\": " << result.total_time_ns << ",\n"
+             << "      \"iterations\": " << result.iterations << ",\n"
+             << "      \"avg_time_ns\": " << result.avg_time_ns << "\n"
+             << "    }" << (i < results.size() - 1 ? "," : "") << "\n";
+    }
+    file << "  ]\n}\n";
+
+    file.close();
+    std::cout << "Results exported to JSON: " << filename << std::endl;
+}
+
+// Helper function to run a benchmark with warmup
+template <typename F>
+BenchmarkResult runBenchmark(const std::string &name, F &&func, double rng_overhead = 0.0) {
+    std::cout << "\n--- Benchmark: " << name << " ---" << std::endl;
+
+    // Warmup phase
+    if (config.warmup_iterations > 0) {
+        std::cout << "Warming up with " << config.warmup_iterations << " iterations..."
+                  << std::endl;
+        for (int i = 0; i < config.warmup_iterations; i++) {
+            func(i);
+        }
+    }
+
+    // Measurement phase
+    std::cout << "Running " << config.measurement_iterations << " iterations..." << std::endl;
+    auto start = std::chrono::high_resolution_clock::now();
+
+    for (int i = 0; i < config.measurement_iterations; i++) {
+        func(i);
+        if (config.debug && i % 100000 == 0) {
+            std::cout << "Progress: " << (i * 100 / config.measurement_iterations) << "%"
+                      << std::endl;
+        }
+    }
+
+    auto end = std::chrono::high_resolution_clock::now();
+    auto duration = std::chrono::duration_cast<std::chrono::nanoseconds>(end - start);
+
+    double avg_time = (double)duration.count() / config.measurement_iterations;
+    if (rng_overhead > 0) {
+        avg_time -= rng_overhead;
+    }
+
+    std::cout << "Total time: " << duration.count() << " ns" << std::endl;
+    std::cout << "Average time per operation: " << avg_time << " ns" << std::endl;
+    if (rng_overhead > 0) {
+        std::cout << "  (RNG overhead of " << rng_overhead << " ns has been subtracted)"
+                  << std::endl;
+    }
+
+    return {name, static_cast<long long>(avg_time * config.measurement_iterations),
+            config.measurement_iterations, avg_time};
+}
+
+// Benchmark just the RNG overhead
+BenchmarkResult measureRNGOverhead() {
+    std::mt19937 rng(42);
+    std::vector<const char *> names(config.measurement_iterations);
+    std::vector<UnwindFailureKind> kinds(config.measurement_iterations);
+    std::vector<int> indices(config.measurement_iterations);
+
+    return runBenchmark("RNG Overhead", [&](int i) {
+        indices[i] = rng() % NUM_NAMES;
+        names[i] = TEST_NAMES[indices[i]];
+        kinds[i] = static_cast<UnwindFailureKind>(rng() % 3);
+    });
+}
+
+// Main benchmark function
+void benchmarkUnwindFailures() {
+    UnwindFailures failures;
+    results.clear(); // Clear any previous results
+
+    std::cout << "=== Benchmarking UnwindFailures ===" << std::endl;
+    std::cout << "Configuration:" << std::endl;
+    std::cout << "  Warmup iterations: " << config.warmup_iterations << std::endl;
+    std::cout << "  Measurement iterations: " << config.measurement_iterations << std::endl;
+    std::cout << "  Number of test names: " << NUM_NAMES << std::endl;
+    std::cout << "  Debug mode: " << (config.debug ? "enabled" : "disabled") << std::endl;
+
+    // First measure RNG overhead
+    std::cout << "\nMeasuring RNG overhead..." << std::endl;
+    auto rng_overhead = measureRNGOverhead();
+    double overhead_per_op = rng_overhead.avg_time_ns;
+    std::cout << "RNG overhead per operation: " << overhead_per_op << " ns" << std::endl;
+
+    // Create RNG for actual benchmarks
+    std::mt19937 rng(42);
+
+    // Run actual benchmarks with RNG inline and overhead subtracted internally
+    results.push_back(runBenchmark(
+            "Record Single Failure Kind",
+            [&](int) {
+                int idx = rng() % NUM_NAMES;
+                auto kind = static_cast<UnwindFailureKind>(rng() % 3);
+                failures.record(UNWIND_FAILURE_STUB, TEST_NAMES[idx]);
+            },
+            overhead_per_op));
+
+    results.push_back(runBenchmark(
+        "Record Mixed Failures",
+        [&](int) {
+            int idx = rng() % NUM_NAMES;
+            auto kind = static_cast<UnwindFailureKind>(rng() % 3);
+            failures.record(kind, TEST_NAMES[idx]);
+        },
+        overhead_per_op));
+
+    results.push_back(runBenchmark(
+        "Find Name",
+        [&](int) {
+            int idx = rng() % NUM_NAMES;
+            failures.findName(TEST_NAMES[idx]);
+        },
+        overhead_per_op));
+
+    results.push_back(runBenchmark(
+        "Count Failures with Mixed Kinds",
+        [&](int) {
+            int idx = rng() % NUM_NAMES;
+            auto kind = static_cast<UnwindFailureKind>(rng() % 3);
+            failures.count(TEST_NAMES[idx], kind);
+        },
+        overhead_per_op));
+
+    // For merge benchmark, we'll pre-populate the collections since that's not part of what we're
+    // measuring
+    UnwindFailures failures1;
+    UnwindFailures failures2;
+    // Use a smaller number of items for pre-population to avoid overflow
+    const int prePopulateCount = std::min(1000, config.measurement_iterations / 2);
+    for (int i = 0; i < prePopulateCount; i++) {
+        int idx = rng() % NUM_NAMES;
+        auto kind = static_cast<UnwindFailureKind>(rng() % 3);
+        failures1.record(kind, TEST_NAMES[idx]);
+        failures2.record(kind, TEST_NAMES[idx]);
+    }
+
+    results.push_back(runBenchmark("Merge Failures", [&](int) {
+        failures1.merge(failures2);
+    }));
+
+    std::cout << "\n=== Benchmark Complete ===" << std::endl;
+}
+
+void printUsage(const char *programName) {
+    std::cout << "Usage: " << programName << " [options]\n"
+              << "Options:\n"
+              << "  --csv <filename>    Export results to CSV file\n"
+              << "  --json <filename>   Export results to JSON file\n"
+              << "  --warmup <n>        Number of warmup iterations (default: 100000)\n"
+              << "  --iterations <n>    Number of measurement iterations (default: 1000000)\n"
+              << "  --debug            Enable debug output\n"
+              << "  -h, --help         Show this help message\n";
+}
+
+int main(int argc, char *argv[]) {
+    // Parse command line arguments
+    for (int i = 1; i < argc; i++) {
+        if (strcmp(argv[i], "--csv") == 0 && i + 1 < argc) {
+            config.csv_file = argv[++i];
+        } else if (strcmp(argv[i], "--json") == 0 && i + 1 < argc) {
+            config.json_file = argv[++i];
+        } else if (strcmp(argv[i], "--warmup") == 0 && i + 1 < argc) {
+            config.warmup_iterations = std::atoi(argv[++i]);
+        } else if (strcmp(argv[i], "--iterations") == 0 && i + 1 < argc) {
+            config.measurement_iterations = std::atoi(argv[++i]);
+        } else if (strcmp(argv[i], "--debug") == 0) {
+            config.debug = true;
+        } else if (strcmp(argv[i], "-h") == 0 || strcmp(argv[i], "--help") == 0) {
+            printUsage(argv[0]);
+            return 0;
+        } else {
+            std::cerr << "Unknown option: " << argv[i] << std::endl;
+            printUsage(argv[0]);
+            return 1;
+        }
+    }
+
+    std::cout << "Running UnwindFailures benchmark..." << std::endl;
+    benchmarkUnwindFailures();
+
+    // Export results if requested
+    if (!config.csv_file.empty()) {
+        exportResultsToCSV(config.csv_file);
+    }
+    if (!config.json_file.empty()) {
+        exportResultsToJSON(config.json_file);
+    }
+
+    return 0;
+}