db: avoid `#include`ing malloc and jemalloc simultaneously

Summary:
This fixes a compilation failure on Linux when the system libc is not
glibc. jemalloc's configure script incorrectly assumes that glibc is
always used on Linux systems, producing glibc-style signatures; when
the system libc is e.g. musl, the following error is observed:

```
  [  0%] Building CXX object CMakeFiles/rocksdb.dir/db/db_impl.cc.o
  In file included from /go/src/github.com/cockroachdb/cockroach/c-deps/rocksdb.src/table/block.h:19:0,
                   from /go/src/github.com/cockroachdb/cockroach/c-deps/rocksdb.src/db/db_impl.cc:77:
  /x-tools/x86_64-unknown-linux-musl/x86_64-unknown-linux-musl/sysroot/usr/include/malloc.h:19:8: error: declaration of 'size_t malloc_usable_size(void*)' has a different exception specifier
   size_t malloc_usable_size(void *);
          ^~~~~~~~~~~~~~~~~~
  In file included from /go/src/github.com/cockroachdb/cockroach/c-deps/rocksdb.src/db/db_impl.cc:20:0:
  /go/native/x86_64-unknown-linux-musl/jemalloc/include/jemalloc/jemalloc.h:78:33: note: from previous declaration 'size_t malloc_usable_size(void*) throw ()'
   #  define je_malloc_usable_size malloc_usable_size
                                   ^
  /go/native/x86_64-unknown-linux-musl/jemalloc/include/jemalloc/jemalloc.h:239:41: note: in expansion of macro 'je_malloc_usable_size'
   JEMALLOC_EXPORT size_t JEMALLOC_NOTHROW je_malloc_usable_size(
                                           ^~~~~~~~~~~~~~~~~~~~~
  CMakeFiles/rocksdb.dir/build.make:350: recipe for target 'CMakeFiles/rocksdb.dir/db/db_impl.cc.o' failed
```

This works around the issue by rearranging the sources such that
jemalloc's headers are never in the same scope as the system's malloc
header. The jemalloc issue has been reported as well, see:
https://github.com/jemalloc/jemalloc/issues/778.

cc tschottdorf
Closes https://github.com/facebook/rocksdb/pull/2188

Differential Revision: D5163048

Pulled By: siying

fbshipit-source-id: c553125458892def175c1be5682b0330d80b2a0d

CMakeLists.txt

@@ -358,6 +358,7 @@ set(SOURCES
         db/internal_stats.cc
         db/log_reader.cc
         db/log_writer.cc
+        db/malloc_stats.cc
         db/managed_iterator.cc
         db/memtable.cc
         db/memtable_list.cc

TARGETS

@@ -83,6 +83,7 @@ cpp_library(
       "db/internal_stats.cc",
       "db/log_reader.cc",
       "db/log_writer.cc",
+      "db/malloc_stats.cc",
       "db/managed_iterator.cc",
       "db/memtable.cc",
       "db/memtable_list.cc",

db/db_impl.cc

@@ -18,9 +18,6 @@
 #ifdef OS_SOLARIS
 #include <alloca.h>
 #endif
-#ifdef ROCKSDB_JEMALLOC
-#include "jemalloc/jemalloc.h"
-#endif
 
 #include <algorithm>
 #include <climits>
@@ -46,6 +43,7 @@
 #include "db/job_context.h"
 #include "db/log_reader.h"
 #include "db/log_writer.h"
+#include "db/malloc_stats.h"
 #include "db/managed_iterator.h"
 #include "db/memtable.h"
 #include "db/memtable_list.h"
@@ -370,39 +368,6 @@ void DBImpl::PrintStatistics() {
   }
 }
 
-#ifndef ROCKSDB_LITE
-#ifdef ROCKSDB_JEMALLOC
-typedef struct {
-  char* cur;
-  char* end;
-} MallocStatus;
-
-static void GetJemallocStatus(void* mstat_arg, const char* status) {
-  MallocStatus* mstat = reinterpret_cast<MallocStatus*>(mstat_arg);
-  size_t status_len = status ? strlen(status) : 0;
-  size_t buf_size = (size_t)(mstat->end - mstat->cur);
-  if (!status_len || status_len > buf_size) {
-    return;
-  }
-
-  snprintf(mstat->cur, buf_size, "%s", status);
-  mstat->cur += status_len;
-}
-#endif  // ROCKSDB_JEMALLOC
-
-static void DumpMallocStats(std::string* stats) {
-#ifdef ROCKSDB_JEMALLOC
-  MallocStatus mstat;
-  const unsigned int kMallocStatusLen = 1000000;
-  std::unique_ptr<char[]> buf{new char[kMallocStatusLen + 1]};
-  mstat.cur = buf.get();
-  mstat.end = buf.get() + kMallocStatusLen;
-  je_malloc_stats_print(GetJemallocStatus, &mstat, "");
-  stats->append(buf.get());
-#endif  // ROCKSDB_JEMALLOC
-}
-#endif  // !ROCKSDB_LITE
-
 void DBImpl::MaybeDumpStats() {
   mutex_.Lock();
   unsigned int stats_dump_period_sec =

db/malloc_stats.cc

@@ -0,0 +1,52 @@
+//  Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
+//  This source code is licensed under the BSD-style license found in the
+//  LICENSE file in the root directory of this source tree. An additional grant
+//  of patent rights can be found in the PATENTS file in the same directory.
+//
+// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file. See the AUTHORS file for names of contributors.
+
+#include "db/malloc_stats.h"
+
+#ifndef ROCKSDB_LITE
+#include <memory>
+#include <string.h>
+
+namespace rocksdb {
+
+#ifdef ROCKSDB_JEMALLOC
+#include "jemalloc/jemalloc.h"
+
+typedef struct {
+  char* cur;
+  char* end;
+} MallocStatus;
+
+static void GetJemallocStatus(void* mstat_arg, const char* status) {
+  MallocStatus* mstat = reinterpret_cast<MallocStatus*>(mstat_arg);
+  size_t status_len = status ? strlen(status) : 0;
+  size_t buf_size = (size_t)(mstat->end - mstat->cur);
+  if (!status_len || status_len > buf_size) {
+    return;
+  }
+
+  snprintf(mstat->cur, buf_size, "%s", status);
+  mstat->cur += status_len;
+}
+#endif  // ROCKSDB_JEMALLOC
+
+void DumpMallocStats(std::string* stats) {
+#ifdef ROCKSDB_JEMALLOC
+  MallocStatus mstat;
+  const unsigned int kMallocStatusLen = 1000000;
+  std::unique_ptr<char[]> buf{new char[kMallocStatusLen + 1]};
+  mstat.cur = buf.get();
+  mstat.end = buf.get() + kMallocStatusLen;
+  je_malloc_stats_print(GetJemallocStatus, &mstat, "");
+  stats->append(buf.get());
+#endif  // ROCKSDB_JEMALLOC
+}
+
+}
+#endif  // !ROCKSDB_LITE

db/malloc_stats.h

@@ -0,0 +1,22 @@
+//  Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
+//  This source code is licensed under the BSD-style license found in the
+//  LICENSE file in the root directory of this source tree. An additional grant
+//  of patent rights can be found in the PATENTS file in the same directory.
+//
+// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file. See the AUTHORS file for names of contributors.
+
+#pragma once
+
+#ifndef ROCKSDB_LITE
+
+#include <string>
+
+namespace rocksdb {
+
+void DumpMallocStats(std::string*);
+
+}
+
+#endif  // !ROCKSDB_LITE

src.mk

@@ -35,6 +35,7 @@ LIB_SOURCES =                                                   \
   db/internal_stats.cc                                          \
   db/log_reader.cc                                              \
   db/log_writer.cc                                              \
+  db/malloc_stats.cc                                            \
   db/managed_iterator.cc                                        \
   db/memtable.cc                                                \
   db/memtable_list.cc                                           \