[profile] in-process mergeing support (part-2)

(Part-1 merging API is in profile runtime)

This patch implements a portable file opening API
with exclusive access for the process. In-process
profile merge requires profile file update to be
atomic/fully sychronized.

llvm-svn: 271864

compiler-rt/lib/profile/CMakeLists.txt

@@ -22,6 +22,22 @@ int main() {
       }
 " COMPILER_RT_TARGET_HAS_ATOMICS)
 
+CHECK_CXX_SOURCE_COMPILES("
+#if defined(__linux__)
+#include <unistd.h>
+#endif
+#include <fcntl.h>
+int fd;
+int main() {
+ struct flock s_flock;
+
+ s_flock.l_type = F_WRLCK;
+ fcntl(fd, F_SETLKW, &s_flock);
+ return 0;
+}
+
+" COMPILER_RT_TARGET_HAS_FCNTL_LCK)
+
 add_custom_target(profile)
 
 set(PROFILE_SOURCES
@@ -55,6 +71,12 @@ if(COMPILER_RT_TARGET_HAS_ATOMICS)
      -DCOMPILER_RT_HAS_ATOMICS=1)
 endif() 
 
+if(COMPILER_RT_TARGET_HAS_FCNTL_LCK)
+ set(EXTRA_FLAGS
+     ${EXTRA_FLAGS}
+     -DCOMPILER_RT_HAS_FCNTL_LCK=1)
+endif()
+
 if(APPLE)
   add_compiler_rt_runtime(clang_rt.profile
     STATIC

compiler-rt/lib/profile/InstrProfilingUtil.c

@@ -12,9 +12,15 @@
 
 #ifdef _WIN32
 #include <direct.h>
+#include <windows.h>
 #else
 #include <sys/stat.h>
 #include <sys/types.h>
+#if defined(__linux__)
+#include <unistd.h>
+#endif
+#include <fcntl.h>
+#include <errno.h>
 #endif
 
 #ifdef COMPILER_RT_HAS_UNAME
@@ -35,7 +41,7 @@ void __llvm_profile_recursive_mkdir(char *path) {
 #ifdef _WIN32
     _mkdir(path);
 #else
-    mkdir(path, 0755);  /* Some of these will fail, ignore it. */
+    mkdir(path, 0755); /* Some of these will fail, ignore it. */
 #endif
     path[i] = save;
   }
@@ -70,4 +76,51 @@ int lprofGetHostName(char *Name, int Len) {
 }
 #endif
 
+FILE *lprofOpenFileEx(const char *ProfileName) {
+  FILE *f;
+  int fd;
+#ifdef COMPILER_RT_HAS_FCNTL_LCK
+  struct flock s_flock;
 
+  s_flock.l_whence = SEEK_SET;
+  s_flock.l_start = 0;
+  s_flock.l_len = 0; /* Until EOF.  */
+  s_flock.l_pid = getpid();
+
+  s_flock.l_type = F_WRLCK;
+  fd = open(ProfileName, O_RDWR | O_CREAT, 0666);
+  if (fd < 0)
+    return 0;
+
+  while (fcntl(fd, F_SETLKW, &s_flock) && errno == EINTR)
+    continue;
+
+  f = fdopen(fd, "r+b");
+#elif defined(_WIN32)
+  HANDLE h = CreateFile(ProfileName, GENERIC_READ | GENERIC_WRITE, 0, 0,
+                        OPEN_ALWAYS, FILE_ATTRIBUTE_NORMAL, 0);
+  if (h == INVALID_HANDLE_VALUE)
+    return 0;
+
+  fd = _open_osfhandle((intptr_t)h, 0);
+  if (fd == -1) {
+    CloseHandle(h);
+    return 0;
+  }
+
+  f = _fdopen(fd, "r+b");
+  if (f == 0) {
+    CloseHandle(h);
+    return 0;
+  }
+#else
+  /* Worst case no locking applied.  */
+  PROF_WARN("Concurrent file access is not supported : %s\n", "lack file locking");
+  fd = open(ProfileName, O_RDWR | O_CREAT, 0666);
+  if (fd < 0)
+    return 0;
+  f = fdopen(fd, "r+b");
+#endif
+
+  return f;
+}

compiler-rt/lib/profile/InstrProfilingUtil.h

@@ -11,10 +11,15 @@
 #define PROFILE_INSTRPROFILINGUTIL_H
 
 #include <stddef.h>
+#include <stdio.h>
 
 /*! \brief Create a directory tree. */
 void __llvm_profile_recursive_mkdir(char *Pathname);
 
+/*! Open file \c Filename for read+write with write
+ * lock for exclusive access. The caller will block
+ * if the lock is already held by another process. */
+FILE *lprofOpenFileEx(const char *Filename);
 /* PS4 doesn't have getenv. Define a shim. */
 #if __ORBIS__
 static inline char *getenv(const char *name) { return NULL; }

compiler-rt/test/profile/Inputs/instrprof-file_ex.c

@@ -0,0 +1,59 @@
+/* This is a test case where the parent process forks 10
+ * children which contend to write to the same file. With
+ * file locking support, the data from each child should not
+ * be lost.
+ */
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <sys/wait.h>
+
+extern FILE *lprofOpenFileEx(const char *);
+int main(int argc, char *argv[]) {
+  pid_t tid;
+  FILE *F;
+  const char *FN;
+  int child[10];
+  int c;
+  int i;
+
+  if (argc < 2) {
+    fprintf(stderr, "Requires one argument \n");
+    exit(1);
+  }
+  FN = argv[1];
+  truncate(FN, 0);
+
+  for (i = 0; i < 10; i++) {
+    c = fork();
+    // in child: 
+    if (c == 0) {
+      FILE *F = lprofOpenFileEx(FN);
+      if (!F) {
+        fprintf(stderr, "Can not open file %s from child\n", FN);
+        exit(1);
+      }
+      fseek(F, 0, SEEK_END);
+      fprintf(F, "Dump from Child %d\n", i + 11);
+      fclose(F);
+      exit(0);
+    } else {
+      child[i] = c;
+    }
+  }
+
+  // In parent
+  for (i = 0; i < 10; i++) {
+    int child_status;
+    if ((tid = waitpid(child[i], &child_status, 0) == -1))
+      break;
+  }
+  F = lprofOpenFileEx(FN);
+  if (!F) {
+    fprintf(stderr, "Can not open file %s from parent\n", FN);
+    exit(1);
+  }
+  fseek(F, 0, SEEK_END);
+  fprintf(F, "Dump from parent %d\n", i + 11);
+  return 0;
+}

compiler-rt/test/profile/Linux/instrprof-file_ex.test

@@ -0,0 +1,16 @@
+RUN: mkdir -p %t.d
+RUN: %clang_profgen -fprofile-instr-generate %S/../Inputs/instrprof-file_ex.c -o %t
+RUN: %run %t %t.d/run.dump
+RUN: sort %t.d/run.dump | FileCheck %s
+
+CHECK: Dump from Child 11
+CHECK-NEXT: Dump from Child 12
+CHECK-NEXT: Dump from Child 13
+CHECK-NEXT: Dump from Child 14
+CHECK-NEXT: Dump from Child 15
+CHECK-NEXT: Dump from Child 16
+CHECK-NEXT: Dump from Child 17
+CHECK-NEXT: Dump from Child 18
+CHECK-NEXT: Dump from Child 19
+CHECK-NEXT: Dump from Child 20
+CHECK-NEXT: Dump from parent 21