Update to leveldb 1.6

Highlights
----------
Mmap at most 1000 files on Posix to improve performance for large databases.
Support for more architectures (thanks to Alexander K.)

Building and porting
--------------------
HP/UX support (issue 126)
AtomicPointer for ia64 (issue 123)
Sparc v9 support (issue 124)
Atomic ops for powerpc
Use -fno-builtin-memcmp only when using g++
Simplify IOS build rules (issue 114)
Use CXXFLAGS instead of CFLAGS when invoking C++ compiler (issue 118)
Fix snappy shared library problem (issue 94)
Fix shared library installation path regression
Endian-ness detection tweak for FreeBSD

Bug fixes
---------
Stop ignoring FLAGS_open_files in db_bench
Make bloom test behavior agnostic to endian-ness

Performance
-----------
Limit number of mmapped files to 1000 to improve perf for large dbs
Do not delay for 1 second on shutdown path (issue 125)

Misc
----
Make InMemoryEnv return a no-op logger
C binding now has a wrapper for free (issue 117)
Add thread-safety annotations
Added an in-process lock table (issue 120)
Make RandomAccessFile and SequentialFile non-copyable

Makefile

@@ -15,7 +15,8 @@ OPT ?= -O2 -DNDEBUG       # (A) Production use (optimized mode)
 #-----------------------------------------------
 
 # detect what platform we're building on
-$(shell ./build_detect_platform build_config.mk)
+$(shell CC=$(CC) CXX=$(CXX) TARGET_OS=$(TARGET_OS) \
+    ./build_detect_platform build_config.mk ./)
 # this file is generated by the previous line to set build flags and sources
 include build_config.mk
 
@@ -70,7 +71,7 @@ SHARED = $(SHARED1)
 else
 # Update db.h if you change these.
 SHARED_MAJOR = 1
-SHARED_MINOR = 5
+SHARED_MINOR = 6
 SHARED1 = libleveldb.$(PLATFORM_SHARED_EXT)
 SHARED2 = $(SHARED1).$(SHARED_MAJOR)
 SHARED3 = $(SHARED1).$(SHARED_MAJOR).$(SHARED_MINOR)
@@ -82,7 +83,7 @@ $(SHARED2): $(SHARED3)
 endif
 
 $(SHARED3):
-	$(CXX) $(LDFLAGS) $(PLATFORM_SHARED_LDFLAGS)$(SHARED2) $(CXXFLAGS) $(PLATFORM_SHARED_CFLAGS) $(SOURCES) -o $(SHARED3)
+	$(CXX) $(SOURCES) $(LDFLAGS) $(PLATFORM_SHARED_LDFLAGS)$(INSTALL_PATH)$(SHARED2) $(CXXFLAGS) $(PLATFORM_SHARED_CFLAGS) -o $(SHARED3)
 
 endif  # PLATFORM_SHARED_EXT
 
@@ -179,14 +180,14 @@ IOSVERSION=$(shell defaults read $(PLATFORMSROOT)/iPhoneOS.platform/version CFBu
 
 .cc.o:
 	mkdir -p ios-x86/$(dir $@)
-	$(SIMULATORROOT)/usr/bin/$(CXX) $(CXXFLAGS) -isysroot $(SIMULATORROOT)/SDKs/iPhoneSimulator$(IOSVERSION).sdk -arch i686 -c $< -o ios-x86/$@
+	$(CXX) $(CXXFLAGS) -isysroot $(SIMULATORROOT)/SDKs/iPhoneSimulator$(IOSVERSION).sdk -arch i686 -c $< -o ios-x86/$@
 	mkdir -p ios-arm/$(dir $@)
 	$(DEVICEROOT)/usr/bin/$(CXX) $(CXXFLAGS) -isysroot $(DEVICEROOT)/SDKs/iPhoneOS$(IOSVERSION).sdk -arch armv6 -arch armv7 -c $< -o ios-arm/$@
 	lipo ios-x86/$@ ios-arm/$@ -create -output $@
 
 .c.o:
 	mkdir -p ios-x86/$(dir $@)
-	$(SIMULATORROOT)/usr/bin/$(CC) $(CFLAGS) -isysroot $(SIMULATORROOT)/SDKs/iPhoneSimulator$(IOSVERSION).sdk -arch i686 -c $< -o ios-x86/$@
+	$(CC) $(CFLAGS) -isysroot $(SIMULATORROOT)/SDKs/iPhoneSimulator$(IOSVERSION).sdk -arch i686 -c $< -o ios-x86/$@
 	mkdir -p ios-arm/$(dir $@)
 	$(DEVICEROOT)/usr/bin/$(CC) $(CFLAGS) -isysroot $(DEVICEROOT)/SDKs/iPhoneOS$(IOSVERSION).sdk -arch armv6 -arch armv7 -c $< -o ios-arm/$@
 	lipo ios-x86/$@ ios-arm/$@ -create -output $@

TODO

@@ -7,6 +7,7 @@ db
   within [start_key..end_key]?  For Chrome, deletion of obsolete
   object stores, etc. can be done in the background anyway, so
   probably not that important.
+- There have been requests for MultiGet.
 
 After a range is completely deleted, what gets rid of the
 corresponding files if we do no future changes to that range.  Make

build_detect_platform

@@ -23,8 +23,9 @@
 #
 
 OUTPUT=$1
-if test -z "$OUTPUT"; then
+PREFIX=$2
-  echo "usage: $0 <output-filename>" >&2
+if test -z "$OUTPUT" || test -z "$PREFIX"; then
+  echo "usage: $0 <output-filename> <directory_prefix>" >&2
   exit 1
 fi
 
@@ -55,58 +56,72 @@ PLATFORM_SHARED_LDFLAGS="-shared -Wl,-soname -Wl,"
 PLATFORM_SHARED_CFLAGS="-fPIC"
 PLATFORM_SHARED_VERSIONED=true
 
-# On GCC, we pick libc's memcmp over GCC's memcmp via -fno-builtin-memcmp
+MEMCMP_FLAG=
+if [ "$CXX" = "g++" ]; then
+    # Use libc's memcmp instead of GCC's memcmp.  This results in ~40%
+    # performance improvement on readrandom under gcc 4.4.3 on Linux/x86.
+    MEMCMP_FLAG="-fno-builtin-memcmp"
+fi
+
 case "$TARGET_OS" in
     Darwin)
         PLATFORM=OS_MACOSX
-        COMMON_FLAGS="-fno-builtin-memcmp -DOS_MACOSX"
+        COMMON_FLAGS="$MEMCMP_FLAG -DOS_MACOSX"
         PLATFORM_SHARED_EXT=dylib
         PLATFORM_SHARED_LDFLAGS="-dynamiclib -install_name "
         PORT_FILE=port/port_posix.cc
         ;;
     Linux)
         PLATFORM=OS_LINUX
-        COMMON_FLAGS="-fno-builtin-memcmp -pthread -DOS_LINUX"
+        COMMON_FLAGS="$MEMCMP_FLAG -pthread -DOS_LINUX"
         PLATFORM_LDFLAGS="-pthread"
         PORT_FILE=port/port_posix.cc
         ;;
     SunOS)
         PLATFORM=OS_SOLARIS
-        COMMON_FLAGS="-fno-builtin-memcmp -D_REENTRANT -DOS_SOLARIS"
+        COMMON_FLAGS="$MEMCMP_FLAG -D_REENTRANT -DOS_SOLARIS"
         PLATFORM_LDFLAGS="-lpthread -lrt"
         PORT_FILE=port/port_posix.cc
         ;;
     FreeBSD)
         PLATFORM=OS_FREEBSD
-        COMMON_FLAGS="-fno-builtin-memcmp -D_REENTRANT -DOS_FREEBSD"
+        COMMON_FLAGS="$MEMCMP_FLAG -D_REENTRANT -DOS_FREEBSD"
         PLATFORM_LDFLAGS="-lpthread"
         PORT_FILE=port/port_posix.cc
         ;;
     NetBSD)
         PLATFORM=OS_NETBSD
-        COMMON_FLAGS="-fno-builtin-memcmp -D_REENTRANT -DOS_NETBSD"
+        COMMON_FLAGS="$MEMCMP_FLAG -D_REENTRANT -DOS_NETBSD"
         PLATFORM_LDFLAGS="-lpthread -lgcc_s"
         PORT_FILE=port/port_posix.cc
         ;;
     OpenBSD)
         PLATFORM=OS_OPENBSD
-        COMMON_FLAGS="-fno-builtin-memcmp -D_REENTRANT -DOS_OPENBSD"
+        COMMON_FLAGS="$MEMCMP_FLAG -D_REENTRANT -DOS_OPENBSD"
         PLATFORM_LDFLAGS="-pthread"
         PORT_FILE=port/port_posix.cc
         ;;
     DragonFly)
         PLATFORM=OS_DRAGONFLYBSD
-        COMMON_FLAGS="-fno-builtin-memcmp -D_REENTRANT -DOS_DRAGONFLYBSD"
+        COMMON_FLAGS="$MEMCMP_FLAG -D_REENTRANT -DOS_DRAGONFLYBSD"
         PLATFORM_LDFLAGS="-lpthread"
         PORT_FILE=port/port_posix.cc
         ;;
     OS_ANDROID_CROSSCOMPILE)
         PLATFORM=OS_ANDROID
-        COMMON_FLAGS="-fno-builtin-memcmp -D_REENTRANT -DOS_ANDROID -DLEVELDB_PLATFORM_POSIX"
+        COMMON_FLAGS="$MEMCMP_FLAG -D_REENTRANT -DOS_ANDROID -DLEVELDB_PLATFORM_POSIX"
         PLATFORM_LDFLAGS=""  # All pthread features are in the Android C library
         PORT_FILE=port/port_posix.cc
         CROSS_COMPILE=true
         ;;
+    HP-UX)
+        PLATFORM=OS_HPUX
+        COMMON_FLAGS="$MEMCMP_FLAG -D_REENTRANT -DOS_HPUX"
+        PLATFORM_LDFLAGS="-pthread"
+        PORT_FILE=port/port_posix.cc
+        # man ld: +h internal_name
+        PLATFORM_SHARED_LDFLAGS="-shared -Wl,+h -Wl,"
+        ;;
     *)
         echo "Unknown platform!" >&2
         exit 1
@@ -116,11 +131,13 @@ esac
 # except for the test and benchmark files. By default, find will output a list
 # of all files matching either rule, so we need to append -print to make the
 # prune take effect.
-DIRS="util db table"
+DIRS="$PREFIX/db $PREFIX/util $PREFIX/table"
+
 set -f # temporarily disable globbing so that our patterns aren't expanded
 PRUNE_TEST="-name *test*.cc -prune"
 PRUNE_BENCH="-name *_bench.cc -prune"
-PORTABLE_FILES=`find $DIRS $PRUNE_TEST -o $PRUNE_BENCH -o -name '*.cc' -print | sort | tr "\n" " "`
+PORTABLE_FILES=`find $DIRS $PRUNE_TEST -o $PRUNE_BENCH -o -name '*.cc' -print | sort | sed "s,^$PREFIX/,," | tr "\n" " "`
+
 set +f # re-enable globbing
 
 # The sources consist of the portable files, plus the platform-specific port
@@ -133,7 +150,7 @@ if [ "$CROSS_COMPILE" = "true" ]; then
     true
 else
     # If -std=c++0x works, use <cstdatomic>.  Otherwise use port_posix.h.
-    $CXX $CFLAGS -std=c++0x -x c++ - -o /dev/null 2>/dev/null  <<EOF
+    $CXX $CXXFLAGS -std=c++0x -x c++ - -o /dev/null 2>/dev/null  <<EOF
       #include <cstdatomic>
       int main() {}
 EOF
@@ -146,7 +163,7 @@ EOF
 
     # Test whether Snappy library is installed
     # http://code.google.com/p/snappy/
-    $CXX $CFLAGS -x c++ - -o /dev/null 2>/dev/null  <<EOF
+    $CXX $CXXFLAGS -x c++ - -o /dev/null 2>/dev/null  <<EOF
       #include <snappy.h>
       int main() {}
 EOF
@@ -156,7 +173,7 @@ EOF
     fi
 
     # Test whether tcmalloc is available
-    $CXX $CFLAGS -x c++ - -o /dev/null -ltcmalloc 2>/dev/null  <<EOF
+    $CXX $CXXFLAGS -x c++ - -o /dev/null -ltcmalloc 2>/dev/null  <<EOF
       int main() {}
 EOF
     if [ "$?" = 0 ]; then

db/c.cc

@@ -578,4 +578,8 @@ void leveldb_env_destroy(leveldb_env_t* env) {
   delete env;
 }
 
+void leveldb_free(void* ptr) {
+  free(ptr);
+}
+
 }  // end extern "C"

db/c_test.c

@@ -204,6 +204,12 @@ int main(int argc, char** argv) {
   CheckCondition(err != NULL);
   Free(&err);
 
+  StartPhase("leveldb_free");
+  db = leveldb_open(options, dbname, &err);
+  CheckCondition(err != NULL);
+  leveldb_free(err);
+  err = NULL;
+
   StartPhase("open");
   leveldb_options_set_create_if_missing(options, 1);
   db = leveldb_open(options, dbname, &err);

db/db_bench.cc

@@ -693,6 +693,7 @@ class Benchmark {
     options.create_if_missing = !FLAGS_use_existing_db;
     options.block_cache = cache_;
     options.write_buffer_size = FLAGS_write_buffer_size;
+    options.max_open_files = FLAGS_open_files;
     options.filter_policy = filter_policy_;
     Status s = DB::Open(options, FLAGS_db, &db_);
     if (!s.ok()) {

db/db_impl.cc

@@ -609,7 +609,11 @@ void DBImpl::BackgroundCall() {
   assert(bg_compaction_scheduled_);
   if (!shutting_down_.Acquire_Load()) {
     Status s = BackgroundCompaction();
-    if (!s.ok()) {
+    if (s.ok()) {
+      // Success
+    } else if (shutting_down_.Acquire_Load()) {
+      // Error most likely due to shutdown; do not wait
+    } else {
       // Wait a little bit before retrying background compaction in
       // case this is an environmental problem and we do not want to
       // chew up resources for failed compactions for the duration of

db/db_impl.h

@@ -13,6 +13,7 @@
 #include "leveldb/db.h"
 #include "leveldb/env.h"
 #include "port/port.h"
+#include "port/thread_annotations.h"
 
 namespace leveldb {
 
@@ -71,7 +72,7 @@ class DBImpl : public DB {
   // Recover the descriptor from persistent storage.  May do a significant
   // amount of work to recover recently logged updates.  Any changes to
   // be made to the descriptor are added to *edit.
-  Status Recover(VersionEdit* edit);
+  Status Recover(VersionEdit* edit) EXCLUSIVE_LOCKS_REQUIRED(mutex_);
 
   void MaybeIgnoreError(Status* s) const;
 
@@ -80,27 +81,34 @@ class DBImpl : public DB {
 
   // Compact the in-memory write buffer to disk.  Switches to a new
   // log-file/memtable and writes a new descriptor iff successful.
-  Status CompactMemTable();
+  Status CompactMemTable()
+      EXCLUSIVE_LOCKS_REQUIRED(mutex_);
 
   Status RecoverLogFile(uint64_t log_number,
                         VersionEdit* edit,
-                        SequenceNumber* max_sequence);
+                        SequenceNumber* max_sequence)
+      EXCLUSIVE_LOCKS_REQUIRED(mutex_);
 
-  Status WriteLevel0Table(MemTable* mem, VersionEdit* edit, Version* base);
+  Status WriteLevel0Table(MemTable* mem, VersionEdit* edit, Version* base)
+      EXCLUSIVE_LOCKS_REQUIRED(mutex_);
 
-  Status MakeRoomForWrite(bool force /* compact even if there is room? */);
+  Status MakeRoomForWrite(bool force /* compact even if there is room? */)
+      EXCLUSIVE_LOCKS_REQUIRED(mutex_);
   WriteBatch* BuildBatchGroup(Writer** last_writer);
 
-  void MaybeScheduleCompaction();
+  void MaybeScheduleCompaction() EXCLUSIVE_LOCKS_REQUIRED(mutex_);
   static void BGWork(void* db);
   void BackgroundCall();
-  Status BackgroundCompaction();
+  Status BackgroundCompaction() EXCLUSIVE_LOCKS_REQUIRED(mutex_);
-  void CleanupCompaction(CompactionState* compact);
+  void CleanupCompaction(CompactionState* compact)
-  Status DoCompactionWork(CompactionState* compact);
+      EXCLUSIVE_LOCKS_REQUIRED(mutex_);
+  Status DoCompactionWork(CompactionState* compact)
+      EXCLUSIVE_LOCKS_REQUIRED(mutex_);
 
   Status OpenCompactionOutputFile(CompactionState* compact);
   Status FinishCompactionOutputFile(CompactionState* compact, Iterator* input);
-  Status InstallCompactionResults(CompactionState* compact);
+  Status InstallCompactionResults(CompactionState* compact)
+      EXCLUSIVE_LOCKS_REQUIRED(mutex_);
 
   // Constant after construction
   Env* const env_;

db/db_test.cc

@@ -1442,6 +1442,12 @@ TEST(DBTest, DBOpen_Options) {
   db = NULL;
 }
 
+TEST(DBTest, Locking) {
+  DB* db2 = NULL;
+  Status s = DB::Open(CurrentOptions(), dbname_, &db2);
+  ASSERT_TRUE(!s.ok()) << "Locking did not prevent re-opening db";
+}
+
 // Check that number of files does not grow when we are out of space
 TEST(DBTest, NoSpace) {
   Options options = CurrentOptions();

db/version_set.h

@@ -21,6 +21,7 @@
 #include "db/dbformat.h"
 #include "db/version_edit.h"
 #include "port/port.h"
+#include "port/thread_annotations.h"
 
 namespace leveldb {
 
@@ -159,7 +160,8 @@ class VersionSet {
   // current version.  Will release *mu while actually writing to the file.
   // REQUIRES: *mu is held on entry.
   // REQUIRES: no other thread concurrently calls LogAndApply()
-  Status LogAndApply(VersionEdit* edit, port::Mutex* mu);
+  Status LogAndApply(VersionEdit* edit, port::Mutex* mu)
+      EXCLUSIVE_LOCKS_REQUIRED(mu);
 
   // Recover the last saved descriptor from persistent storage.
   Status Recover();

doc/bench/db_bench_sqlite3.cc

@@ -618,7 +618,7 @@ class Benchmark {
         ErrorCheck(status);
 
         // Execute read statement
-        while ((status = sqlite3_step(read_stmt)) == SQLITE_ROW);
+        while ((status = sqlite3_step(read_stmt)) == SQLITE_ROW) {}
         StepErrorCheck(status);
 
         // Reset SQLite statement for another use

doc/index.html

@@ -408,7 +408,7 @@ The optional <code>FilterPolicy</code> mechanism can be used to reduce
 the number of disk reads substantially.
 <pre>
    leveldb::Options options;
-   options.filter_policy = NewBloomFilter(10);
+   options.filter_policy = NewBloomFilterPolicy(10);
    leveldb::DB* db;
    leveldb::DB::Open(options, "/tmp/testdb", &amp;db);
    ... use the database ...

helpers/memenv/memenv.cc

@@ -221,6 +221,11 @@ class WritableFileImpl : public WritableFile {
   FileState* file_;
 };
 
+class NoOpLogger : public Logger {
+ public:
+  virtual void Logv(const char* format, va_list ap) { }
+};
+
 class InMemoryEnv : public EnvWrapper {
  public:
   explicit InMemoryEnv(Env* base_env) : EnvWrapper(base_env) { }
@@ -358,6 +363,11 @@ class InMemoryEnv : public EnvWrapper {
     return Status::OK();
   }
 
+  virtual Status NewLogger(const std::string& fname, Logger** result) {
+    *result = new NoOpLogger;
+    return Status::OK();
+  }
+
  private:
   // Map from filenames to FileState objects, representing a simple file system.
   typedef std::map<std::string, FileState*> FileSystem;

include/leveldb/c.h

@@ -28,6 +28,7 @@
   be true on entry:
      *errptr == NULL
      *errptr points to a malloc()ed null-terminated error message
+       (On Windows, *errptr must have been malloc()-ed by this library.)
   On success, a leveldb routine leaves *errptr unchanged.
   On failure, leveldb frees the old value of *errptr and
   set *errptr to a malloc()ed error message.
@@ -268,6 +269,15 @@ extern void leveldb_cache_destroy(leveldb_cache_t* cache);
 extern leveldb_env_t* leveldb_create_default_env();
 extern void leveldb_env_destroy(leveldb_env_t*);
 
+/* Utility */
+
+/* Calls free(ptr).
+   REQUIRES: ptr was malloc()-ed and returned by one of the routines
+   in this file.  Note that in certain cases (typically on Windows), you
+   may need to call this routine instead of free(ptr) to dispose of
+   malloc()-ed memory returned by this library. */
+extern void leveldb_free(void* ptr);
+
 #ifdef __cplusplus
 }  /* end extern "C" */
 #endif

include/leveldb/db.h

@@ -14,7 +14,7 @@ namespace leveldb {
 
 // Update Makefile if you change these
 static const int kMajorVersion = 1;
-static const int kMinorVersion = 5;
+static const int kMinorVersion = 6;
 
 struct Options;
 struct ReadOptions;

include/leveldb/env.h

@@ -175,6 +175,11 @@ class SequentialFile {
   //
   // REQUIRES: External synchronization
   virtual Status Skip(uint64_t n) = 0;
+
+ private:
+  // No copying allowed
+  SequentialFile(const SequentialFile&);
+  void operator=(const SequentialFile&);
 };
 
 // A file abstraction for randomly reading the contents of a file.
@@ -194,6 +199,11 @@ class RandomAccessFile {
   // Safe for concurrent use by multiple threads.
   virtual Status Read(uint64_t offset, size_t n, Slice* result,
                       char* scratch) const = 0;
+
+ private:
+  // No copying allowed
+  RandomAccessFile(const RandomAccessFile&);
+  void operator=(const RandomAccessFile&);
 };
 
 // A file abstraction for sequential writing.  The implementation

port/atomic_pointer.h

@@ -36,6 +36,8 @@
 #define ARCH_CPU_X86_FAMILY 1
 #elif defined(__ARMEL__)
 #define ARCH_CPU_ARM_FAMILY 1
+#elif defined(__ppc__) || defined(__powerpc__) || defined(__powerpc64__)
+#define ARCH_CPU_PPC_FAMILY 1
 #endif
 
 namespace leveldb {
@@ -91,6 +93,15 @@ inline void MemoryBarrier() {
 }
 #define LEVELDB_HAVE_MEMORY_BARRIER
 
+// PPC
+#elif defined(ARCH_CPU_PPC_FAMILY) && defined(__GNUC__)
+inline void MemoryBarrier() {
+  // TODO for some powerpc expert: is there a cheaper suitable variant?
+  // Perhaps by having separate barriers for acquire and release ops.
+  asm volatile("sync" : : : "memory");
+}
+#define LEVELDB_HAVE_MEMORY_BARRIER
+
 #endif
 
 // AtomicPointer built using platform-specific MemoryBarrier()
@@ -136,6 +147,66 @@ class AtomicPointer {
   }
 };
 
+// Atomic pointer based on sparc memory barriers
+#elif defined(__sparcv9) && defined(__GNUC__)
+class AtomicPointer {
+ private:
+  void* rep_;
+ public:
+  AtomicPointer() { }
+  explicit AtomicPointer(void* v) : rep_(v) { }
+  inline void* Acquire_Load() const {
+    void* val;
+    __asm__ __volatile__ (
+        "ldx [%[rep_]], %[val] \n\t"
+         "membar #LoadLoad|#LoadStore \n\t"
+        : [val] "=r" (val)
+        : [rep_] "r" (&rep_)
+        : "memory");
+    return val;
+  }
+  inline void Release_Store(void* v) {
+    __asm__ __volatile__ (
+        "membar #LoadStore|#StoreStore \n\t"
+        "stx %[v], [%[rep_]] \n\t"
+        :
+        : [rep_] "r" (&rep_), [v] "r" (v)
+        : "memory");
+  }
+  inline void* NoBarrier_Load() const { return rep_; }
+  inline void NoBarrier_Store(void* v) { rep_ = v; }
+};
+
+// Atomic pointer based on ia64 acq/rel
+#elif defined(__ia64) && defined(__GNUC__)
+class AtomicPointer {
+ private:
+  void* rep_;
+ public:
+  AtomicPointer() { }
+  explicit AtomicPointer(void* v) : rep_(v) { }
+  inline void* Acquire_Load() const {
+    void* val    ;
+    __asm__ __volatile__ (
+        "ld8.acq %[val] = [%[rep_]] \n\t"
+        : [val] "=r" (val)
+        : [rep_] "r" (&rep_)
+        : "memory"
+        );
+    return val;
+  }
+  inline void Release_Store(void* v) {
+    __asm__ __volatile__ (
+        "st8.rel [%[rep_]] = %[v]  \n\t"
+        :
+        : [rep_] "r" (&rep_), [v] "r" (v)
+        : "memory"
+        );
+  }
+  inline void* NoBarrier_Load() const { return rep_; }
+  inline void NoBarrier_Store(void* v) { rep_ = v; }
+};
+
 // We have neither MemoryBarrier(), nor <cstdatomic>
 #else
 #error Please implement AtomicPointer for this platform.
@@ -145,6 +216,7 @@ class AtomicPointer {
 #undef LEVELDB_HAVE_MEMORY_BARRIER
 #undef ARCH_CPU_X86_FAMILY
 #undef ARCH_CPU_ARM_FAMILY
+#undef ARCH_CPU_PPC_FAMILY
 
 }  // namespace port
 }  // namespace leveldb

port/port_posix.h

@@ -21,13 +21,20 @@
   #else
     #define PLATFORM_IS_LITTLE_ENDIAN false
   #endif
-#elif defined(OS_FREEBSD) || defined(OS_OPENBSD) || defined(OS_NETBSD) ||\
+#elif defined(OS_FREEBSD)
+  #include <sys/types.h>
+  #include <sys/endian.h>
+  #define PLATFORM_IS_LITTLE_ENDIAN (_BYTE_ORDER == _LITTLE_ENDIAN)
+#elif defined(OS_OPENBSD) || defined(OS_NETBSD) ||\
       defined(OS_DRAGONFLYBSD) || defined(OS_ANDROID)
   #include <sys/types.h>
   #include <sys/endian.h>
+#elif defined(OS_HPUX)
+  #define PLATFORM_IS_LITTLE_ENDIAN false
 #else
   #include <endian.h>
 #endif
+
 #include <pthread.h>
 #ifdef SNAPPY
 #include <snappy.h>
@@ -42,7 +49,7 @@
 
 #if defined(OS_MACOSX) || defined(OS_SOLARIS) || defined(OS_FREEBSD) ||\
     defined(OS_NETBSD) || defined(OS_OPENBSD) || defined(OS_DRAGONFLYBSD) ||\
-    defined(OS_ANDROID)
+    defined(OS_ANDROID) || defined(OS_HPUX)
 // Use fread/fwrite/fflush on platforms without _unlocked variants
 #define fread_unlocked fread
 #define fwrite_unlocked fwrite

port/thread_annotations.h

@@ -0,0 +1,59 @@
+// Copyright (c) 2012 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.
+
+#ifndef STORAGE_LEVELDB_PORT_THREAD_ANNOTATIONS_H
+
+// Some environments provide custom macros to aid in static thread-safety
+// analysis.  Provide empty definitions of such macros unless they are already
+// defined.
+
+#ifndef EXCLUSIVE_LOCKS_REQUIRED
+#define EXCLUSIVE_LOCKS_REQUIRED(...)
+#endif
+
+#ifndef SHARED_LOCKS_REQUIRED
+#define SHARED_LOCKS_REQUIRED(...)
+#endif
+
+#ifndef LOCKS_EXCLUDED
+#define LOCKS_EXCLUDED(...)
+#endif
+
+#ifndef LOCK_RETURNED
+#define LOCK_RETURNED(x)
+#endif
+
+#ifndef LOCKABLE
+#define LOCKABLE
+#endif
+
+#ifndef SCOPED_LOCKABLE
+#define SCOPED_LOCKABLE
+#endif
+
+#ifndef EXCLUSIVE_LOCK_FUNCTION
+#define EXCLUSIVE_LOCK_FUNCTION(...)
+#endif
+
+#ifndef SHARED_LOCK_FUNCTION
+#define SHARED_LOCK_FUNCTION(...)
+#endif
+
+#ifndef EXCLUSIVE_TRYLOCK_FUNCTION
+#define EXCLUSIVE_TRYLOCK_FUNCTION(...)
+#endif
+
+#ifndef SHARED_TRYLOCK_FUNCTION
+#define SHARED_TRYLOCK_FUNCTION(...)
+#endif
+
+#ifndef UNLOCK_FUNCTION
+#define UNLOCK_FUNCTION(...)
+#endif
+
+#ifndef NO_THREAD_SAFETY_ANALYSIS
+#define NO_THREAD_SAFETY_ANALYSIS
+#endif
+
+#endif  // STORAGE_LEVELDB_PORT_THREAD_ANNOTATIONS_H

table/block.cc

@@ -162,8 +162,8 @@ class Block::Iter : public Iterator {
   }
 
   virtual void Seek(const Slice& target) {
-    // Binary search in restart array to find the first restart point
+    // Binary search in restart array to find the last restart point
-    // with a key >= target
+    // with a key < target
     uint32_t left = 0;
     uint32_t right = num_restarts_ - 1;
     while (left < right) {

util/bloom_test.cc

@@ -4,6 +4,7 @@
 
 #include "leveldb/filter_policy.h"
 
+#include "util/coding.h"
 #include "util/logging.h"
 #include "util/testharness.h"
 #include "util/testutil.h"
@@ -13,8 +14,8 @@ namespace leveldb {
 static const int kVerbose = 1;
 
 static Slice Key(int i, char* buffer) {
-  memcpy(buffer, &i, sizeof(i));
+  EncodeFixed32(buffer, i);
-  return Slice(buffer, sizeof(i));
+  return Slice(buffer, sizeof(uint32_t));
 }
 
 class BloomTest {

util/coding.cc

@@ -7,20 +7,20 @@
 namespace leveldb {
 
 void EncodeFixed32(char* buf, uint32_t value) {
-#if __BYTE_ORDER == __LITTLE_ENDIAN
+  if (port::kLittleEndian) {
     memcpy(buf, &value, sizeof(value));
-#else
+  } else {
     buf[0] = value & 0xff;
     buf[1] = (value >> 8) & 0xff;
     buf[2] = (value >> 16) & 0xff;
     buf[3] = (value >> 24) & 0xff;
-#endif
+  }
 }
 
 void EncodeFixed64(char* buf, uint64_t value) {
-#if __BYTE_ORDER == __LITTLE_ENDIAN
+  if (port::kLittleEndian) {
     memcpy(buf, &value, sizeof(value));
-#else
+  } else {
     buf[0] = value & 0xff;
     buf[1] = (value >> 8) & 0xff;
     buf[2] = (value >> 16) & 0xff;
@@ -29,7 +29,7 @@ void EncodeFixed64(char* buf, uint64_t value) {
     buf[5] = (value >> 40) & 0xff;
     buf[6] = (value >> 48) & 0xff;
     buf[7] = (value >> 56) & 0xff;
-#endif
+  }
 }
 
 void PutFixed32(std::string* dst, uint32_t value) {

util/env_posix.cc

@@ -3,6 +3,7 @@
 // found in the LICENSE file. See the AUTHORS file for names of contributors.
 
 #include <deque>
+#include <set>
 #include <dirent.h>
 #include <errno.h>
 #include <fcntl.h>
@@ -23,6 +24,7 @@
 #include "leveldb/slice.h"
 #include "port/port.h"
 #include "util/logging.h"
+#include "util/mutexlock.h"
 #include "util/posix_logger.h"
 
 namespace leveldb {
@@ -90,18 +92,75 @@ class PosixRandomAccessFile: public RandomAccessFile {
   }
 };
 
+// Helper class to limit mmap file usage so that we do not end up
+// running out virtual memory or running into kernel performance
+// problems for very large databases.
+class MmapLimiter {
+ public:
+  // Up to 1000 mmaps for 64-bit binaries; none for smaller pointer sizes.
+  MmapLimiter() {
+    SetAllowed(sizeof(void*) >= 8 ? 1000 : 0);
+  }
+
+  // If another mmap slot is available, acquire it and return true.
+  // Else return false.
+  bool Acquire() {
+    if (GetAllowed() <= 0) {
+      return false;
+    }
+    MutexLock l(&mu_);
+    intptr_t x = GetAllowed();
+    if (x <= 0) {
+      return false;
+    } else {
+      SetAllowed(x - 1);
+      return true;
+    }
+  }
+
+  // Release a slot acquired by a previous call to Acquire() that returned true.
+  void Release() {
+    MutexLock l(&mu_);
+    SetAllowed(GetAllowed() + 1);
+  }
+
+ private:
+  port::Mutex mu_;
+  port::AtomicPointer allowed_;
+
+  intptr_t GetAllowed() const {
+    return reinterpret_cast<intptr_t>(allowed_.Acquire_Load());
+  }
+
+  // REQUIRES: mu_ must be held
+  void SetAllowed(intptr_t v) {
+    allowed_.Release_Store(reinterpret_cast<void*>(v));
+  }
+
+  MmapLimiter(const MmapLimiter&);
+  void operator=(const MmapLimiter&);
+};
+
 // mmap() based random-access
 class PosixMmapReadableFile: public RandomAccessFile {
  private:
   std::string filename_;
   void* mmapped_region_;
   size_t length_;
+  MmapLimiter* limiter_;
 
  public:
   // base[0,length-1] contains the mmapped contents of the file.
-  PosixMmapReadableFile(const std::string& fname, void* base, size_t length)
+  PosixMmapReadableFile(const std::string& fname, void* base, size_t length,
-      : filename_(fname), mmapped_region_(base), length_(length) { }
+                        MmapLimiter* limiter)
-  virtual ~PosixMmapReadableFile() { munmap(mmapped_region_, length_); }
+      : filename_(fname), mmapped_region_(base), length_(length),
+        limiter_(limiter) {
+  }
+
+  virtual ~PosixMmapReadableFile() {
+    munmap(mmapped_region_, length_);
+    limiter_->Release();
+  }
 
   virtual Status Read(uint64_t offset, size_t n, Slice* result,
                       char* scratch) const {
@@ -300,6 +359,25 @@ static int LockOrUnlock(int fd, bool lock) {
 class PosixFileLock : public FileLock {
  public:
   int fd_;
+  std::string name_;
+};
+
+// Set of locked files.  We keep a separate set instead of just
+// relying on fcntrl(F_SETLK) since fcntl(F_SETLK) does not provide
+// any protection against multiple uses from the same process.
+class PosixLockTable {
+ private:
+  port::Mutex mu_;
+  std::set<std::string> locked_files_;
+ public:
+  bool Insert(const std::string& fname) {
+    MutexLock l(&mu_);
+    return locked_files_.insert(fname).second;
+  }
+  void Remove(const std::string& fname) {
+    MutexLock l(&mu_);
+    locked_files_.erase(fname);
+  }
 };
 
 class PosixEnv : public Env {
@@ -329,19 +407,21 @@ class PosixEnv : public Env {
     int fd = open(fname.c_str(), O_RDONLY);
     if (fd < 0) {
       s = IOError(fname, errno);
-    } else if (sizeof(void*) >= 8) {
+    } else if (mmap_limit_.Acquire()) {
-      // Use mmap when virtual address-space is plentiful.
       uint64_t size;
       s = GetFileSize(fname, &size);
       if (s.ok()) {
         void* base = mmap(NULL, size, PROT_READ, MAP_SHARED, fd, 0);
         if (base != MAP_FAILED) {
-          *result = new PosixMmapReadableFile(fname, base, size);
+          *result = new PosixMmapReadableFile(fname, base, size, &mmap_limit_);
         } else {
           s = IOError(fname, errno);
         }
       }
       close(fd);
+      if (!s.ok()) {
+        mmap_limit_.Release();
+      }
     } else {
       *result = new PosixRandomAccessFile(fname, fd);
     }
@@ -430,12 +510,17 @@ class PosixEnv : public Env {
     int fd = open(fname.c_str(), O_RDWR | O_CREAT, 0644);
     if (fd < 0) {
       result = IOError(fname, errno);
+    } else if (!locks_.Insert(fname)) {
+      close(fd);
+      result = Status::IOError("lock " + fname, "already held by process");
     } else if (LockOrUnlock(fd, true) == -1) {
       result = IOError("lock " + fname, errno);
       close(fd);
+      locks_.Remove(fname);
     } else {
       PosixFileLock* my_lock = new PosixFileLock;
       my_lock->fd_ = fd;
+      my_lock->name_ = fname;
       *lock = my_lock;
     }
     return result;
@@ -447,6 +532,7 @@ class PosixEnv : public Env {
     if (LockOrUnlock(my_lock->fd_, false) == -1) {
       result = IOError("unlock", errno);
     }
+    locks_.Remove(my_lock->name_);
     close(my_lock->fd_);
     delete my_lock;
     return result;
@@ -523,6 +609,9 @@ class PosixEnv : public Env {
   struct BGItem { void* arg; void (*function)(void*); };
   typedef std::deque<BGItem> BGQueue;
   BGQueue queue_;
+
+  PosixLockTable locks_;
+  MmapLimiter mmap_limit_;
 };
 
 PosixEnv::PosixEnv() : page_size_(getpagesize()),

util/mutexlock.h

@@ -6,6 +6,7 @@
 #define STORAGE_LEVELDB_UTIL_MUTEXLOCK_H_
 
 #include "port/port.h"
+#include "port/thread_annotations.h"
 
 namespace leveldb {
 
@@ -19,12 +20,13 @@ namespace leveldb {
 //     ... some complex code, possibly with multiple return paths ...
 //   }
 
-class MutexLock {
+class SCOPED_LOCKABLE MutexLock {
  public:
-  explicit MutexLock(port::Mutex *mu) : mu_(mu) {
+  explicit MutexLock(port::Mutex *mu) EXCLUSIVE_LOCK_FUNCTION(mu)
+      : mu_(mu)  {
     this->mu_->Lock();
   }
-  ~MutexLock() { this->mu_->Unlock(); }
+  ~MutexLock() UNLOCK_FUNCTION() { this->mu_->Unlock(); }
 
  private:
   port::Mutex *const mu_;