src/hotspot/share/jfr/recorder/repository/jfrEmergencyDump.cpp

@@ -43,10 +43,11 @@
 static const char vm_error_filename_fmt[] = "hs_err_pid%p.jfr";
 static const char vm_oom_filename_fmt[] = "hs_oom_pid%p.jfr";
 static const char vm_soe_filename_fmt[] = "hs_soe_pid%p.jfr";
 static const char chunk_file_jfr_ext[] = ".jfr";
 static const size_t iso8601_len = 19; // "YYYY-MM-DDTHH:MM:SS"
+static fio_fd emergency_fd = invalid_fd;
 
 static fio_fd open_exclusivly(const char* path) {
   return os::open(path, O_CREAT | O_RDWR, S_IREAD | S_IWRITE);
 }
 

@@ -210,11 +211,11 @@
 
 const char* const RepositoryIterator::next() const {
   return _iterator >= _files->length() ? NULL : fully_qualified(_files->at(_iterator++));
 }
 
-static void write_emergency_file(fio_fd emergency_fd, const RepositoryIterator& iterator) {
+static void write_emergency_file(const RepositoryIterator& iterator) {
   assert(emergency_fd != invalid_fd, "invariant");
   const size_t size_of_file_copy_block = 1 * M; // 1 mb
   jbyte* const file_copy_block = NEW_RESOURCE_ARRAY_RETURN_NULL(jbyte, size_of_file_copy_block);
   if (file_copy_block == NULL) {
     return;

@@ -245,18 +246,17 @@
       }
     }
   }
 }
 
-static const char* create_emergency_dump_path() {
-  char* buffer = NEW_RESOURCE_ARRAY_RETURN_NULL(char, JVM_MAXPATHLEN);
-  if (NULL == buffer) {
-    return NULL;
-  }
+// "emergency_dump_path" have to be allocated JVM_MAXPATHLEN or larger.
+static void create_emergency_dump_path(char* emergency_dump_path) {
+  char buffer[JVM_MAXPATHLEN];
+  emergency_dump_path[0] = '\0';
   const char* const cwd = os::get_current_directory(buffer, JVM_MAXPATHLEN);
   if (NULL == cwd) {
-    return NULL;
+    return;
   }
   size_t pos = strlen(cwd);
   const int fsep_len = jio_snprintf(&buffer[pos], JVM_MAXPATHLEN - pos, "%s", os::file_separator());
   const char* filename_fmt = NULL;
   // fetch specific error cause

@@ -268,25 +268,18 @@
       filename_fmt = vm_soe_filename_fmt;
       break;
     default:
       filename_fmt = vm_error_filename_fmt;
   }
-  char* emergency_dump_path = NULL;
   pos += fsep_len;
   if (Arguments::copy_expand_pid(filename_fmt, strlen(filename_fmt), &buffer[pos], JVM_MAXPATHLEN - pos)) {
-    const size_t emergency_filename_length = strlen(buffer);
-    emergency_dump_path = NEW_RESOURCE_ARRAY_RETURN_NULL(char, emergency_filename_length + 1);
-    if (NULL == emergency_dump_path) {
-      return NULL;
-    }
-    strncpy(emergency_dump_path, buffer, emergency_filename_length + 1);
+    strncpy(emergency_dump_path, buffer, JVM_MAXPATHLEN);
   }
-  if (emergency_dump_path != NULL) {
+  if (emergency_dump_path[0] != '\0') {
     log_info(jfr)( // For user, should not be "jfr, system"
       "Attempting to recover JFR data, emergency jfr file: %s", emergency_dump_path);
   }
-  return emergency_dump_path;
 }
 
 // Caller needs ResourceMark
 static const char* create_emergency_chunk_path(const char* repository_path) {
   assert(repository_path != NULL, "invariant");

@@ -307,28 +300,39 @@
   // append the individual substrings
   jio_snprintf(chunk_path, chunkname_max_len, "%s%s%s%s", repository_path, os::file_separator(), date_time_buffer, chunk_file_jfr_ext);
   return chunk_path;
 }
 
-static fio_fd emergency_dump_file_descriptor() {
-  ResourceMark rm;
-  const char* const emergency_dump_path = create_emergency_dump_path();
-  return emergency_dump_path != NULL ? open_exclusivly(emergency_dump_path) : invalid_fd;
+void JfrEmergencyDump::setup_emergency_dump_file_descriptor() {
+  assert(emergency_fd == invalid_fd, "invariant");
+  char emergency_dump_path[JVM_MAXPATHLEN];
+  create_emergency_dump_path(emergency_dump_path);
+  emergency_fd = (emergency_dump_path[0] != '\0') ? open_exclusivly(emergency_dump_path) : invalid_fd;
 }
 
+// Caller needs ResourceMark
 const char* JfrEmergencyDump::build_dump_path(const char* repository_path) {
-  return repository_path == NULL ? create_emergency_dump_path() : create_emergency_chunk_path(repository_path);
+  if (repository_path == NULL) {
+    char* dump_path = NEW_RESOURCE_ARRAY_RETURN_NULL(char, JVM_MAXPATHLEN);
+    if (dump_path == NULL) {
+      return NULL;
+    }
+    create_emergency_dump_path(dump_path);
+    return dump_path;
+  } else {
+    return create_emergency_chunk_path(repository_path);
+  }
 }
 
 void JfrEmergencyDump::on_vm_error(const char* repository_path) {
   assert(repository_path != NULL, "invariant");
   ResourceMark rm;
-  const fio_fd emergency_fd = emergency_dump_file_descriptor();
   if (emergency_fd != invalid_fd) {
     RepositoryIterator iterator(repository_path, strlen(repository_path));
-    write_emergency_file(emergency_fd, iterator);
+    write_emergency_file(iterator);
     os::close(emergency_fd);
+    emergency_fd = invalid_fd;
   }
 }
 
 /*
 * We are just about to exit the VM, so we will be very aggressive