use mmap on 64-bit machines to speed-up reads; small build fixes

git-svn-id: http://leveldb.googlecode.com/svn/trunk@62 62dab493-f737-651d-591e-8d6aee1b9529

8 files changed, 99 insertions, 39 deletions

diff --git a/Makefile b/Makefile
index d337905..c284d4c 100644
--- a/Makefile
+++ b/Makefile
@@ -124,65 +124,65 @@ db_bench: db/db_bench.o $(LIBOBJECTS) $(TESTUTIL)
 	$(CXX) $(LDFLAGS) db/db_bench.o $(LIBOBJECTS) $(TESTUTIL) -o $@
 
 db_bench_sqlite3: doc/bench/db_bench_sqlite3.o $(LIBOBJECTS) $(TESTUTIL)
-	$(CXX) $(LDFLAGS) -lsqlite3 doc/bench/db_bench_sqlite3.o $(LIBOBJECTS) $(TESTUTIL) -o $@
+	$(CXX) -lsqlite3 doc/bench/db_bench_sqlite3.o $(LIBOBJECTS) $(TESTUTIL) -o $@ $(LDFLAGS
 
 db_bench_tree_db: doc/bench/db_bench_tree_db.o $(LIBOBJECTS) $(TESTUTIL)
 	$(CXX) $(LDFLAGS) -lkyotocabinet doc/bench/db_bench_tree_db.o $(LIBOBJECTS) $(TESTUTIL) -o $@
 
 arena_test: util/arena_test.o $(LIBOBJECTS) $(TESTHARNESS)
-	$(CXX) $(LDFLAGS) util/arena_test.o $(LIBOBJECTS) $(TESTHARNESS) -o $@
+	$(CXX) util/arena_test.o $(LIBOBJECTS) $(TESTHARNESS) -o $@ $(LDFLAGS)
 
 c_test: db/c_test.o $(LIBOBJECTS) $(TESTHARNESS)
-	$(CXX) $(LDFLAGS) db/c_test.o $(LIBOBJECTS) $(TESTHARNESS) -o $@
+	$(CXX) db/c_test.o $(LIBOBJECTS) $(TESTHARNESS) -o $@ $(LDFLAGS)
 
 cache_test: util/cache_test.o $(LIBOBJECTS) $(TESTHARNESS)
-	$(CXX) $(LDFLAGS) util/cache_test.o $(LIBOBJECTS) $(TESTHARNESS) -o $@
+	$(CXX) util/cache_test.o $(LIBOBJECTS) $(TESTHARNESS) -o $@ $(LDFLAGS)
 
 coding_test: util/coding_test.o $(LIBOBJECTS) $(TESTHARNESS)
-	$(CXX) $(LDFLAGS) util/coding_test.o $(LIBOBJECTS) $(TESTHARNESS) -o $@
+	$(CXX) util/coding_test.o $(LIBOBJECTS) $(TESTHARNESS) -o $@ $(LDFLAGS)
 
 corruption_test: db/corruption_test.o $(LIBOBJECTS) $(TESTHARNESS)
-	$(CXX) $(LDFLAGS) db/corruption_test.o $(LIBOBJECTS) $(TESTHARNESS) -o $@
+	$(CXX) db/corruption_test.o $(LIBOBJECTS) $(TESTHARNESS) -o $@ $(LDFLAGS)
 
 crc32c_test: util/crc32c_test.o $(LIBOBJECTS) $(TESTHARNESS)
-	$(CXX) $(LDFLAGS) util/crc32c_test.o $(LIBOBJECTS) $(TESTHARNESS) -o $@
+	$(CXX) util/crc32c_test.o $(LIBOBJECTS) $(TESTHARNESS) -o $@ $(LDFLAGS)
 
 db_test: db/db_test.o $(LIBOBJECTS) $(TESTHARNESS)
-	$(CXX) $(LDFLAGS) db/db_test.o $(LIBOBJECTS) $(TESTHARNESS) -o $@
+	$(CXX) db/db_test.o $(LIBOBJECTS) $(TESTHARNESS) -o $@ $(LDFLAGS)
 
 dbformat_test: db/dbformat_test.o $(LIBOBJECTS) $(TESTHARNESS)
-	$(CXX) $(LDFLAGS) db/dbformat_test.o $(LIBOBJECTS) $(TESTHARNESS) -o $@
+	$(CXX) db/dbformat_test.o $(LIBOBJECTS) $(TESTHARNESS) -o $@ $(LDFLAGS)
 
 env_test: util/env_test.o $(LIBOBJECTS) $(TESTHARNESS)
-	$(CXX) $(LDFLAGS) util/env_test.o $(LIBOBJECTS) $(TESTHARNESS) -o $@
+	$(CXX) util/env_test.o $(LIBOBJECTS) $(TESTHARNESS) -o $@ $(LDFLAGS)
 
 filename_test: db/filename_test.o $(LIBOBJECTS) $(TESTHARNESS)
-	$(CXX) $(LDFLAGS) db/filename_test.o $(LIBOBJECTS) $(TESTHARNESS) -o $@
+	$(CXX) db/filename_test.o $(LIBOBJECTS) $(TESTHARNESS) -o $@ $(LDFLAGS)
 
 log_test: db/log_test.o $(LIBOBJECTS) $(TESTHARNESS)
-	$(CXX) $(LDFLAGS) db/log_test.o $(LIBOBJECTS) $(TESTHARNESS) -o $@
+	$(CXX) db/log_test.o $(LIBOBJECTS) $(TESTHARNESS) -o $@ $(LDFLAGS)
 
 table_test: table/table_test.o $(LIBOBJECTS) $(TESTHARNESS)
-	$(CXX) $(LDFLAGS) table/table_test.o $(LIBOBJECTS) $(TESTHARNESS) -o $@
+	$(CXX) table/table_test.o $(LIBOBJECTS) $(TESTHARNESS) -o $@ $(LDFLAGS)
 
 skiplist_test: db/skiplist_test.o $(LIBOBJECTS) $(TESTHARNESS)
-	$(CXX) $(LDFLAGS) db/skiplist_test.o $(LIBOBJECTS) $(TESTHARNESS) -o $@
+	$(CXX) db/skiplist_test.o $(LIBOBJECTS) $(TESTHARNESS) -o $@ $(LDFLAGS)
 
 version_edit_test: db/version_edit_test.o $(LIBOBJECTS) $(TESTHARNESS)
-	$(CXX) $(LDFLAGS) db/version_edit_test.o $(LIBOBJECTS) $(TESTHARNESS) -o $@
+	$(CXX) db/version_edit_test.o $(LIBOBJECTS) $(TESTHARNESS) -o $@ $(LDFLAGS)
 
 version_set_test: db/version_set_test.o $(LIBOBJECTS) $(TESTHARNESS)
-	$(CXX) $(LDFLAGS) db/version_set_test.o $(LIBOBJECTS) $(TESTHARNESS) -o $@
+	$(CXX) db/version_set_test.o $(LIBOBJECTS) $(TESTHARNESS) -o $@ $(LDFLAGS)
 
 write_batch_test: db/write_batch_test.o $(LIBOBJECTS) $(TESTHARNESS)
-	$(CXX) $(LDFLAGS) db/write_batch_test.o $(LIBOBJECTS) $(TESTHARNESS) -o $@
+	$(CXX) db/write_batch_test.o $(LIBOBJECTS) $(TESTHARNESS) -o $@ $(LDFLAGS)
 
 $(MEMENVLIBRARY) : helpers/memenv/memenv.o
 	rm -f $@
 	$(AR) -rs $@ helpers/memenv/memenv.o
 
 memenv_test : helpers/memenv/memenv_test.o $(MEMENVLIBRARY) $(LIBRARY) $(TESTHARNESS)
-	$(CXX) $(LDFLAGS) helpers/memenv/memenv_test.o $(MEMENVLIBRARY) $(LIBRARY) $(TESTHARNESS) -o $@
+	$(CXX) helpers/memenv/memenv_test.o $(MEMENVLIBRARY) $(LIBRARY) $(TESTHARNESS) -o $@ $(LDFLAGS)
 
 ifeq ($(PLATFORM), IOS)
 # For iOS, create universal object files to be used on both the simulator and
diff --git a/table/block.cc b/table/block.cc
index 40aa318..06eb6f8 100644
--- a/table/block.cc
+++ b/table/block.cc
@@ -19,9 +19,10 @@ inline uint32_t Block::NumRestarts() const {
   return DecodeFixed32(data_ + size_ - sizeof(uint32_t));
 }
 
-Block::Block(const char* data, size_t size)
+Block::Block(const char* data, size_t size, bool take_ownership)
     : data_(data),
-      size_(size) {
+      size_(size),
+      owned_(take_ownership) {
   if (size_ < sizeof(uint32_t)) {
     size_ = 0;  // Error marker
   } else {
@@ -35,7 +36,9 @@ Block::Block(const char* data, size_t size)
 }
 
 Block::~Block() {
-  delete[] data_;
+  if (owned_) {
+    delete[] data_;
+  }
 }
 
 // Helper routine: decode the next block entry starting at "p",
diff --git a/table/block.h b/table/block.h
index 9eb6f02..76088a4 100644
--- a/table/block.h
+++ b/table/block.h
@@ -16,8 +16,9 @@ class Comparator;
 class Block {
  public:
   // Initialize the block with the specified contents.
-  // Takes ownership of data[] and will delete[] it when done.
-  Block(const char* data, size_t size);
+  // Takes ownership of data[] and will delete[] it when done iff
+  // "take_ownership is true.
+  Block(const char* data, size_t size, bool take_ownership);
 
   ~Block();
 
@@ -30,6 +31,7 @@ class Block {
   const char* data_;
   size_t size_;
   uint32_t restart_offset_;     // Offset in data_ of restart array
+  bool owned_;                  // Block owns data_[]
 
   // No copying allowed
   Block(const Block&);
diff --git a/table/format.cc b/table/format.cc
index 23728d8..25b85a2 100644
--- a/table/format.cc
+++ b/table/format.cc
@@ -66,8 +66,10 @@ Status Footer::DecodeFrom(Slice* input) {
 Status ReadBlock(RandomAccessFile* file,
                  const ReadOptions& options,
                  const BlockHandle& handle,
-                 Block** block) {
+                 Block** block,
+                 bool* may_cache) {
   *block = NULL;
+  *may_cache = false;
 
   // Read the block contents as well as the type/crc footer.
   // See table_builder.cc for the code that built this structure.
@@ -100,8 +102,14 @@ Status ReadBlock(RandomAccessFile* file,
     case kNoCompression:
       if (data != buf) {
         // File implementation gave us pointer to some other data.
-        // Copy into buf[].
-        memcpy(buf, data, n + kBlockTrailerSize);
+        // Use it directly under the assumption that it will be live
+        // while the file is open.
+        delete[] buf;
+        *block = new Block(data, n, false /* do not take ownership */);
+        *may_cache = false;  // Do not double-cache
+      } else {
+        *block = new Block(buf, n, true /* take ownership */);
+        *may_cache = true;
       }
 
       // Ok
@@ -119,8 +127,8 @@ Status ReadBlock(RandomAccessFile* file,
         return Status::Corruption("corrupted compressed block contents");
       }
       delete[] buf;
-      buf = ubuf;
-      n = ulength;
+      *block = new Block(ubuf, ulength, true /* take ownership */);
+      *may_cache = true;
       break;
     }
     default:
@@ -128,7 +136,6 @@ Status ReadBlock(RandomAccessFile* file,
       return Status::Corruption("bad block type");
   }
 
-  *block = new Block(buf, n);  // Block takes ownership of buf[]
   return Status::OK();
 }
 
diff --git a/table/format.h b/table/format.h
index 2a3e1ac..66a15da 100644
--- a/table/format.h
+++ b/table/format.h
@@ -86,10 +86,13 @@ static const size_t kBlockTrailerSize = 5;
 // Read the block identified by "handle" from "file".  On success,
 // store a pointer to the heap-allocated result in *block and return
 // OK.  On failure store NULL in *block and return non-OK.
+// On success, stores true in *may_cache if the result may be
+// cached, false if it must not be cached.
 extern Status ReadBlock(RandomAccessFile* file,
                         const ReadOptions& options,
                         const BlockHandle& handle,
-                        Block** block);
+                        Block** block,
+                        bool* may_cache);
 
 // Implementation details follow.  Clients should ignore,
 
diff --git a/table/table.cc b/table/table.cc
index 5f9238e..07dcffd 100644
--- a/table/table.cc
+++ b/table/table.cc
@@ -49,7 +49,9 @@ Status Table::Open(const Options& options,
   // Read the index block
   Block* index_block = NULL;
   if (s.ok()) {
-    s = ReadBlock(file, ReadOptions(), footer.index_handle(), &index_block);
+    bool may_cache;  // Ignored result
+    s = ReadBlock(file, ReadOptions(), footer.index_handle(), &index_block,
+                  &may_cache);
   }
 
   if (s.ok()) {
@@ -105,6 +107,7 @@ Iterator* Table::BlockReader(void* arg,
   // can add more features in the future.
 
   if (s.ok()) {
+    bool may_cache;
     if (block_cache != NULL) {
       char cache_key_buffer[16];
       EncodeFixed64(cache_key_buffer, table->rep_->cache_id);
@@ -114,14 +117,14 @@ Iterator* Table::BlockReader(void* arg,
       if (cache_handle != NULL) {
         block = reinterpret_cast<Block*>(block_cache->Value(cache_handle));
       } else {
-        s = ReadBlock(table->rep_->file, options, handle, &block);
-        if (s.ok() && options.fill_cache) {
+        s = ReadBlock(table->rep_->file, options, handle, &block, &may_cache);
+        if (s.ok() && may_cache && options.fill_cache) {
           cache_handle = block_cache->Insert(
               key, block, block->size(), &DeleteCachedBlock);
         }
       }
     } else {
-      s = ReadBlock(table->rep_->file, options, handle, &block);
+      s = ReadBlock(table->rep_->file, options, handle, &block, &may_cache);
     }
   }
 
diff --git a/table/table_test.cc b/table/table_test.cc
index cd85b4b..0c8e676 100644
--- a/table/table_test.cc
+++ b/table/table_test.cc
@@ -205,7 +205,7 @@ class BlockConstructor: public Constructor {
     block_size_ = block_data.size();
     char* block_data_copy = new char[block_size_];
     memcpy(block_data_copy, block_data.data(), block_size_);
-    block_ = new Block(block_data_copy, block_size_);
+    block_ = new Block(block_data_copy, block_size_, true /* take ownership */);
     return Status::OK();
   }
   virtual size_t NumBytes() const { return block_size_; }
diff --git a/util/env_posix.cc b/util/env_posix.cc
index cc73348..cb1f6fc 100644
--- a/util/env_posix.cc
+++ b/util/env_posix.cc
@@ -66,6 +66,7 @@ class PosixSequentialFile: public SequentialFile {
   }
 };
 
+// pread() based random-access
 class PosixRandomAccessFile: public RandomAccessFile {
  private:
   std::string filename_;
@@ -89,6 +90,32 @@ class PosixRandomAccessFile: public RandomAccessFile {
   }
 };
 
+// mmap() based random-access
+class PosixMmapReadableFile: public RandomAccessFile {
+ private:
+  std::string filename_;
+  void* mmapped_region_;
+  size_t length_;
+
+ public:
+  // base[0,length-1] contains the mmapped contents of the file.
+  PosixMmapReadableFile(const std::string& fname, void* base, size_t length)
+      : filename_(fname), mmapped_region_(base), length_(length) { }
+  virtual ~PosixMmapReadableFile() { munmap(mmapped_region_, length_); }
+
+  virtual Status Read(uint64_t offset, size_t n, Slice* result,
+                      char* scratch) const {
+    Status s;
+    if (offset + n > length_) {
+      *result = Slice();
+      s = IOError(filename_, EINVAL);
+    } else {
+      *result = Slice(reinterpret_cast<char*>(mmapped_region_) + offset, n);
+    }
+    return s;
+  }
+};
+
 // We preallocate up to an extra megabyte and use memcpy to append new
 // data to the file.  This is safe since we either properly close the
 // file before reading from it, or for log files, the reading code
@@ -297,13 +324,28 @@ class PosixEnv : public Env {
 
   virtual Status NewRandomAccessFile(const std::string& fname,
                                      RandomAccessFile** result) {
+    *result = NULL;
+    Status s;
     int fd = open(fname.c_str(), O_RDONLY);
     if (fd < 0) {
-      *result = NULL;
-      return IOError(fname, errno);
+      s = IOError(fname, errno);
+    } else if (sizeof(void*) >= 8) {
+      // 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);
+        } else {
+          s = IOError(fname, errno);
+        }
+      }
+      close(fd);
+    } else {
+      *result = new PosixRandomAccessFile(fname, fd);
     }
-    *result = new PosixRandomAccessFile(fname, fd);
-    return Status::OK();
+    return s;
   }
 
   virtual Status NewWritableFile(const std::string& fname,