[XRay][compiler-rt] Support in-memory processing of FDR mode logs

Summary:
This change allows for handling the in-memory data associated with the
FDR mode implementation through the new `__xray_log_process_buffers`
API. With this change, we can now allow users to process the data
in-memory of the process instead of through writing files.

This for example allows users to stream the data of the FDR logging
implementation through network sockets, or through other mechanisms
instead of saving them to local files.

We introduce an FDR-specific flag, for "no_file_flush" which lets the
flushing logic skip opening/writing to files.

This option can be defaulted to `true` when building the compiler-rt
XRay runtime through the `XRAY_FDR_OPTIONS` preprocessor macro.

Reviewers: kpw, echristo, pelikan, eizan

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D46574

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@332208 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 50 insertions, 0 deletions

diff --git a/test/xray/TestCases/Posix/fdr-mode-inmemory.cc b/test/xray/TestCases/Posix/fdr-mode-inmemory.cc
new file mode 100644
index 000000000..db18cc459
--- /dev/null
+++ b/test/xray/TestCases/Posix/fdr-mode-inmemory.cc
@@ -0,0 +1,50 @@
+// RUN: %clangxx_xray -g -std=c++11 %s -o %t -fxray-modes=xray-fdr
+// RUN: rm fdr-inmemory-test-* || true
+// RUN: XRAY_OPTIONS="patch_premain=false xray_logfile_base=fdr-inmemory-test- \
+// RUN:     verbosity=1" \
+// RUN: XRAY_FDR_OPTIONS="no_file_flush=true func_duration_threshold_us=0" \
+// RUN:     %run %t 2>&1 | FileCheck %s
+// RUN: FILES=`find %T -name 'fdr-inmemory-test-*' | wc -l`
+// RUN: [ $FILES -eq 0 ]
+// RUN: rm fdr-inmemory-test-* || true
+//
+// REQUIRES: x86_64-target-arch
+// REQUIRES: built-in-llvm-tree
+
+#include "xray/xray_log_interface.h"
+#include <cassert>
+#include <iostream>
+
+uint64_t var = 0;
+uint64_t buffers = 0;
+[[clang::xray_always_instrument]] void __attribute__((noinline)) f() { ++var; }
+
+int main(int argc, char *argv[]) {
+  assert(__xray_log_select_mode("xray-fdr") ==
+         XRayLogRegisterStatus::XRAY_REGISTRATION_OK);
+  auto status = __xray_log_init_mode(
+      "xray-fdr",
+      "buffer_size=4096:buffer_max=10:func_duration_threshold_us=0");
+  assert(status == XRayLogInitStatus::XRAY_LOG_INITIALIZED);
+  __xray_patch();
+
+  // Create enough entries.
+  for (int i = 0; i != 1 << 20; ++i) {
+    f();
+  }
+
+  // Then we want to verify that we're getting 10 buffers outside of the initial
+  // header.
+  auto finalize_status = __xray_log_finalize();
+  assert(finalize_status == XRayLogInitStatus::XRAY_LOG_FINALIZED);
+  auto process_status =
+      __xray_log_process_buffers([](const char *, XRayBuffer) { ++buffers; });
+  std::cout << "buffers = " << buffers << std::endl;
+  assert(process_status == XRayLogFlushStatus::XRAY_LOG_FLUSHED);
+  auto flush_status = __xray_log_flushLog();
+  assert(flush_status == XRayLogFlushStatus::XRAY_LOG_FLUSHED);
+  // We expect 11 buffers because 1 header buffer + 10 actual FDR buffers.
+  // CHECK: Buffers = 11
+  std::cout << "Buffers = " << buffers << std::endl;
+  return 0;
+}