Speed up Snappy uncompression, new Logger interface.

- Removed one copy of an uncompressed block contents changing
  the signature of Snappy_Uncompress() so it uncompresses into a
  flat array instead of a std::string.
        
  Speeds up readrandom ~10%.

- Instead of a combination of Env/WritableFile, we now have a
  Logger interface that can be easily overridden applications
  that want to supply their own logging.

- Separated out the gcc and Sun Studio parts of atomic_pointer.h
  so we can use 'asm', 'volatile' keywords for Sun Studio.




git-svn-id: https://leveldb.googlecode.com/svn/trunk@39 62dab493-f737-651d-591e-8d6aee1b9529

4 files changed, 132 insertions, 128 deletions

diff --git a/util/env.cc b/util/env.cc
index e5297e7..79e493e 100644
--- a/util/env.cc
+++ b/util/env.cc
@@ -18,14 +18,19 @@ RandomAccessFile::~RandomAccessFile() {
 WritableFile::~WritableFile() {
 }
 
+Logger::~Logger() {
+}
+
 FileLock::~FileLock() {
 }
 
-void Log(Env* env, WritableFile* info_log, const char* format, ...) {
-  va_list ap;
-  va_start(ap, format);
-  env->Logv(info_log, format, ap);
-  va_end(ap);
+void Log(Logger* info_log, const char* format, ...) {
+  if (info_log != NULL) {
+    va_list ap;
+    va_start(ap, format);
+    info_log->Logv(format, ap);
+    va_end(ap);
+  }
 }
 
 Status WriteStringToFile(Env* env, const Slice& data,
diff --git a/util/env_chromium.cc b/util/env_chromium.cc
index 1af525a..975386b 100644
--- a/util/env_chromium.cc
+++ b/util/env_chromium.cc
@@ -23,6 +23,7 @@
 #include "leveldb/slice.h"
 #include "port/port.h"
 #include "util/logging.h"
+#include "util/posix_logger.h"
 
 #if defined(OS_WIN)
 #include <io.h>
@@ -406,9 +407,8 @@ class ChromiumEnv : public Env {
     return Status::OK();
   }
 
-  virtual void Logv(WritableFile* info_log, const char* format, va_list ap) {
-    // TODO(jorlow): We may want to just use Chromium's built in logging.
-
+  // TODO(user,user): Use Chromium's built-in logging?
+  static uint64_t gettid() {
     uint64_t thread_id = 0;
     // Coppied from base/logging.cc.
 #if defined(OS_WIN)
@@ -422,65 +422,17 @@ class ChromiumEnv : public Env {
     pthread_t tid = pthread_self();
     memcpy(&thread_id, &tid, min(sizeof(r), sizeof(tid)));
 #endif
+    return thread_id;
+  }
 
-    // We try twice: the first time with a fixed-size stack allocated buffer,
-    // and the second time with a much larger dynamically allocated buffer.
-    char buffer[500];
-    for (int iter = 0; iter < 2; iter++) {
-      char* base;
-      int bufsize;
-      if (iter == 0) {
-        bufsize = sizeof(buffer);
-        base = buffer;
-      } else {
-        bufsize = 30000;
-        base = new char[bufsize];
-      }
-      char* p = base;
-      char* limit = base + bufsize;
-
-      ::base::Time::Exploded t;
-      ::base::Time::Now().LocalExplode(&t);
-      p += snprintf(p, limit - p,
-                    "%04d/%02d/%02d-%02d:%02d:%02d.%06d %llx ",
-                    t.year,
-                    t.month,
-                    t.day_of_month,
-                    t.hour,
-                    t.minute,
-                    t.second,
-                    static_cast<int>(t.millisecond) * 1000,
-                    static_cast<long long unsigned int>(thread_id));
-
-      // Print the message
-      if (p < limit) {
-        va_list backup_ap;
-        va_copy(backup_ap, ap);
-        p += vsnprintf(p, limit - p, format, backup_ap);
-        va_end(backup_ap);
-      }
-
-      // Truncate to available space if necessary
-      if (p >= limit) {
-        if (iter == 0) {
-          continue;       // Try again with larger buffer
-        } else {
-          p = limit - 1;
-        }
-      }
-
-      // Add newline if necessary
-      if (p == base || p[-1] != '\n') {
-        *p++ = '\n';
-      }
-
-      assert(p <= limit);
-      info_log->Append(Slice(base, p - base));
-      info_log->Flush();
-      if (base != buffer) {
-        delete[] base;
-      }
-      break;
+  virtual Status NewLogger(const std::string& fname, Logger** result) {
+    FILE* f = fopen(fname.c_str(), "w");
+    if (f == NULL) {
+      *result = NULL;
+      return Status::IOError(fname, strerror(errno));
+    } else {
+      *result = new PosixLogger(f, &ChromiumEnv::gettid);
+      return Status::OK();
     }
   }
 
diff --git a/util/env_posix.cc b/util/env_posix.cc
index 46723e2..5127c89 100644
--- a/util/env_posix.cc
+++ b/util/env_posix.cc
@@ -23,6 +23,7 @@
 #include "leveldb/slice.h"
 #include "port/port.h"
 #include "util/logging.h"
+#include "util/posix_logger.h"
 
 namespace leveldb {
 
@@ -427,72 +428,21 @@ class PosixEnv : public Env {
     return Status::OK();
   }
 
-  virtual void Logv(WritableFile* info_log, const char* format, va_list ap) {
+  static uint64_t gettid() {
     pthread_t tid = pthread_self();
     uint64_t thread_id = 0;
     memcpy(&thread_id, &tid, std::min(sizeof(thread_id), sizeof(tid)));
+    return thread_id;
+  }
 
-    // We try twice: the first time with a fixed-size stack allocated buffer,
-    // and the second time with a much larger dynamically allocated buffer.
-    char buffer[500];
-    for (int iter = 0; iter < 2; iter++) {
-      char* base;
-      int bufsize;
-      if (iter == 0) {
-        bufsize = sizeof(buffer);
-        base = buffer;
-      } else {
-        bufsize = 30000;
-        base = new char[bufsize];
-      }
-      char* p = base;
-      char* limit = base + bufsize;
-
-      struct timeval now_tv;
-      gettimeofday(&now_tv, NULL);
-      const time_t seconds = now_tv.tv_sec;
-      struct tm t;
-      localtime_r(&seconds, &t);
-      p += snprintf(p, limit - p,
-                    "%04d/%02d/%02d-%02d:%02d:%02d.%06d %llx ",
-                    t.tm_year + 1900,
-                    t.tm_mon + 1,
-                    t.tm_mday,
-                    t.tm_hour,
-                    t.tm_min,
-                    t.tm_sec,
-                    static_cast<int>(now_tv.tv_usec),
-                    static_cast<long long unsigned int>(thread_id));
-
-      // Print the message
-      if (p < limit) {
-        va_list backup_ap;
-        va_copy(backup_ap, ap);
-        p += vsnprintf(p, limit - p, format, backup_ap);
-        va_end(backup_ap);
-      }
-
-      // Truncate to available space if necessary
-      if (p >= limit) {
-        if (iter == 0) {
-          continue;       // Try again with larger buffer
-        } else {
-          p = limit - 1;
-        }
-      }
-
-      // Add newline if necessary
-      if (p == base || p[-1] != '\n') {
-        *p++ = '\n';
-      }
-
-      assert(p <= limit);
-      info_log->Append(Slice(base, p - base));
-      info_log->Flush();
-      if (base != buffer) {
-        delete[] base;
-      }
-      break;
+  virtual Status NewLogger(const std::string& fname, Logger** result) {
+    FILE* f = fopen(fname.c_str(), "w");
+    if (f == NULL) {
+      *result = NULL;
+      return IOError(fname, errno);
+    } else {
+      *result = new PosixLogger(f, &PosixEnv::gettid);
+      return Status::OK();
     }
   }
 
diff --git a/util/posix_logger.h b/util/posix_logger.h
new file mode 100644
index 0000000..0dbdeaa
--- /dev/null
+++ b/util/posix_logger.h
@@ -0,0 +1,97 @@
+// Copyright 2011 Google Inc. All Rights Reserved.
+// Author: sanjay@google.com (Sanjay Ghemawat)
+//
+// Logger implementation that can be shared by all environments
+// where enough posix functionality is available.
+
+#ifndef STORAGE_LEVELDB_UTIL_POSIX_LOGGER_H_
+#define STORAGE_LEVELDB_UTIL_POSIX_LOGGER_H_
+
+#include <algorithm>
+#include <stdio.h>
+#include <sys/time.h>
+#include <time.h>
+#include "leveldb/env.h"
+
+namespace leveldb {
+
+class PosixLogger : public Logger {
+ private:
+  FILE* file_;
+  uint64_t (*gettid_)();  // Return the thread id for the current thread
+ public:
+  PosixLogger(FILE* f, uint64_t (*gettid)()) : file_(f), gettid_(gettid) { }
+  virtual ~PosixLogger() {
+    fclose(file_);
+  }
+  virtual void Logv(const char* format, va_list ap) {
+    const uint64_t thread_id = (*gettid_)();
+
+    // We try twice: the first time with a fixed-size stack allocated buffer,
+    // and the second time with a much larger dynamically allocated buffer.
+    char buffer[500];
+    for (int iter = 0; iter < 2; iter++) {
+      char* base;
+      int bufsize;
+      if (iter == 0) {
+        bufsize = sizeof(buffer);
+        base = buffer;
+      } else {
+        bufsize = 30000;
+        base = new char[bufsize];
+      }
+      char* p = base;
+      char* limit = base + bufsize;
+
+      struct timeval now_tv;
+      gettimeofday(&now_tv, NULL);
+      const time_t seconds = now_tv.tv_sec;
+      struct tm t;
+      localtime_r(&seconds, &t);
+      p += snprintf(p, limit - p,
+                    "%04d/%02d/%02d-%02d:%02d:%02d.%06d %llx ",
+                    t.tm_year + 1900,
+                    t.tm_mon + 1,
+                    t.tm_mday,
+                    t.tm_hour,
+                    t.tm_min,
+                    t.tm_sec,
+                    static_cast<int>(now_tv.tv_usec),
+                    static_cast<long long unsigned int>(thread_id));
+
+      // Print the message
+      if (p < limit) {
+        va_list backup_ap;
+        va_copy(backup_ap, ap);
+        p += vsnprintf(p, limit - p, format, backup_ap);
+        va_end(backup_ap);
+      }
+
+      // Truncate to available space if necessary
+      if (p >= limit) {
+        if (iter == 0) {
+          continue;       // Try again with larger buffer
+        } else {
+          p = limit - 1;
+        }
+      }
+
+      // Add newline if necessary
+      if (p == base || p[-1] != '\n') {
+        *p++ = '\n';
+      }
+
+      assert(p <= limit);
+      fwrite(base, 1, p - base, file_);
+      fflush(file_);
+      if (base != buffer) {
+        delete[] base;
+      }
+      break;
+    }
+  }
+};
+
+}
+
+#endif  // STORAGE_LEVELDB_UTIL_POSIX_LOGGER_H_