Release LevelDB 1.15v1.15

- switched from mmap based writing to simpler stdio based writing. Has a
  minor impact (0.5 microseconds) on microbenchmarks for asynchronous
  writes. Synchronous writes speed up from 30ms to 10ms on linux/ext4.
  Should be much more reliable on diverse platforms.
- compaction errors now immediately put the database into a read-only
  mode (until it is re-opened). As a downside, a disk going out of
  space and then space being created will require a re-open to recover
  from, whereas previously that would happen automatically. On the
  plus side, many corruption possibilities go away.
- force the DB to enter an error-state so that all future writes fail
  when a synchronous log write succeeds but the sync fails.
- repair now regenerates sstables that exhibit problems
- fix issue 218 - Use native memory barriers on OSX
- fix issue 212 - QNX build is broken
- fix build on iOS with xcode 5
- make tests compile and pass on windows

1 files changed, 57 insertions, 42 deletions

diff --git a/db/db_impl.cc b/db/db_impl.cc
index fa13510..faf5e7d 100644
--- a/db/db_impl.cc
+++ b/db/db_impl.cc
@@ -133,8 +133,7 @@ DBImpl::DBImpl(const Options& raw_options, const std::string& dbname)
       seed_(0),
       tmp_batch_(new WriteBatch),
       bg_compaction_scheduled_(false),
-      manual_compaction_(NULL),
-      consecutive_compaction_errors_(0) {
+      manual_compaction_(NULL) {
   mem_->Ref();
   has_imm_.Release_Store(NULL);
 
@@ -217,6 +216,12 @@ void DBImpl::MaybeIgnoreError(Status* s) const {
 }
 
 void DBImpl::DeleteObsoleteFiles() {
+  if (!bg_error_.ok()) {
+    // After a background error, we don't know whether a new version may
+    // or may not have been committed, so we cannot safely garbage collect.
+    return;
+  }
+
   // Make a set of all of the live files
   std::set<uint64_t> live = pending_outputs_;
   versions_->AddLiveFiles(&live);
@@ -495,7 +500,7 @@ Status DBImpl::WriteLevel0Table(MemTable* mem, VersionEdit* edit,
   return s;
 }
 
-Status DBImpl::CompactMemTable() {
+void DBImpl::CompactMemTable() {
   mutex_.AssertHeld();
   assert(imm_ != NULL);
 
@@ -523,9 +528,9 @@ Status DBImpl::CompactMemTable() {
     imm_ = NULL;
     has_imm_.Release_Store(NULL);
     DeleteObsoleteFiles();
+  } else {
+    RecordBackgroundError(s);
   }
-
-  return s;
 }
 
 void DBImpl::CompactRange(const Slice* begin, const Slice* end) {
@@ -568,16 +573,18 @@ void DBImpl::TEST_CompactRange(int level, const Slice* begin,const Slice* end) {
   }
 
   MutexLock l(&mutex_);
-  while (!manual.done) {
-    while (manual_compaction_ != NULL) {
-      bg_cv_.Wait();
-    }
-    manual_compaction_ = &manual;
-    MaybeScheduleCompaction();
-    while (manual_compaction_ == &manual) {
+  while (!manual.done && !shutting_down_.Acquire_Load() && bg_error_.ok()) {
+    if (manual_compaction_ == NULL) {  // Idle
+      manual_compaction_ = &manual;
+      MaybeScheduleCompaction();
+    } else {  // Running either my compaction or another compaction.
       bg_cv_.Wait();
     }
   }
+  if (manual_compaction_ == &manual) {
+    // Cancel my manual compaction since we aborted early for some reason.
+    manual_compaction_ = NULL;
+  }
 }
 
 Status DBImpl::TEST_CompactMemTable() {
@@ -596,12 +603,22 @@ Status DBImpl::TEST_CompactMemTable() {
   return s;
 }
 
+void DBImpl::RecordBackgroundError(const Status& s) {
+  mutex_.AssertHeld();
+  if (bg_error_.ok()) {
+    bg_error_ = s;
+    bg_cv_.SignalAll();
+  }
+}
+
 void DBImpl::MaybeScheduleCompaction() {
   mutex_.AssertHeld();
   if (bg_compaction_scheduled_) {
     // Already scheduled
   } else if (shutting_down_.Acquire_Load()) {
     // DB is being deleted; no more background compactions
+  } else if (!bg_error_.ok()) {
+    // Already got an error; no more changes
   } else if (imm_ == NULL &&
              manual_compaction_ == NULL &&
              !versions_->NeedsCompaction()) {
@@ -619,30 +636,12 @@ void DBImpl::BGWork(void* db) {
 void DBImpl::BackgroundCall() {
   MutexLock l(&mutex_);
   assert(bg_compaction_scheduled_);
-  if (!shutting_down_.Acquire_Load()) {
-    Status s = BackgroundCompaction();
-    if (s.ok()) {
-      // Success
-      consecutive_compaction_errors_ = 0;
-    } 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
-      // the problem.
-      bg_cv_.SignalAll();  // In case a waiter can proceed despite the error
-      Log(options_.info_log, "Waiting after background compaction error: %s",
-          s.ToString().c_str());
-      mutex_.Unlock();
-      ++consecutive_compaction_errors_;
-      int seconds_to_sleep = 1;
-      for (int i = 0; i < 3 && i < consecutive_compaction_errors_ - 1; ++i) {
-        seconds_to_sleep *= 2;
-      }
-      env_->SleepForMicroseconds(seconds_to_sleep * 1000000);
-      mutex_.Lock();
-    }
+  if (shutting_down_.Acquire_Load()) {
+    // No more background work when shutting down.
+  } else if (!bg_error_.ok()) {
+    // No more background work after a background error.
+  } else {
+    BackgroundCompaction();
   }
 
   bg_compaction_scheduled_ = false;
@@ -653,11 +652,12 @@ void DBImpl::BackgroundCall() {
   bg_cv_.SignalAll();
 }
 
-Status DBImpl::BackgroundCompaction() {
+void DBImpl::BackgroundCompaction() {
   mutex_.AssertHeld();
 
   if (imm_ != NULL) {
-    return CompactMemTable();
+    CompactMemTable();
+    return;
   }
 
   Compaction* c;
@@ -691,6 +691,9 @@ Status DBImpl::BackgroundCompaction() {
     c->edit()->AddFile(c->level() + 1, f->number, f->file_size,
                        f->smallest, f->largest);
     status = versions_->LogAndApply(c->edit(), &mutex_);
+    if (!status.ok()) {
+      RecordBackgroundError(status);
+    }
     VersionSet::LevelSummaryStorage tmp;
     Log(options_.info_log, "Moved #%lld to level-%d %lld bytes %s: %s\n",
         static_cast<unsigned long long>(f->number),
@@ -701,6 +704,9 @@ Status DBImpl::BackgroundCompaction() {
   } else {
     CompactionState* compact = new CompactionState(c);
     status = DoCompactionWork(compact);
+    if (!status.ok()) {
+      RecordBackgroundError(status);
+    }
     CleanupCompaction(compact);
     c->ReleaseInputs();
     DeleteObsoleteFiles();
@@ -714,9 +720,6 @@ Status DBImpl::BackgroundCompaction() {
   } else {
     Log(options_.info_log,
         "Compaction error: %s", status.ToString().c_str());
-    if (options_.paranoid_checks && bg_error_.ok()) {
-      bg_error_ = status;
-    }
   }
 
   if (is_manual) {
@@ -732,7 +735,6 @@ Status DBImpl::BackgroundCompaction() {
     }
     manual_compaction_ = NULL;
   }
-  return status;
 }
 
 void DBImpl::CleanupCompaction(CompactionState* compact) {
@@ -1002,6 +1004,9 @@ Status DBImpl::DoCompactionWork(CompactionState* compact) {
   if (status.ok()) {
     status = InstallCompactionResults(compact);
   }
+  if (!status.ok()) {
+    RecordBackgroundError(status);
+  }
   VersionSet::LevelSummaryStorage tmp;
   Log(options_.info_log,
       "compacted to: %s", versions_->LevelSummary(&tmp));
@@ -1185,13 +1190,23 @@ Status DBImpl::Write(const WriteOptions& options, WriteBatch* my_batch) {
     {
       mutex_.Unlock();
       status = log_->AddRecord(WriteBatchInternal::Contents(updates));
+      bool sync_error = false;
       if (status.ok() && options.sync) {
         status = logfile_->Sync();
+        if (!status.ok()) {
+          sync_error = true;
+        }
       }
       if (status.ok()) {
         status = WriteBatchInternal::InsertInto(updates, mem_);
       }
       mutex_.Lock();
+      if (sync_error) {
+        // The state of the log file is indeterminate: the log record we
+        // just added may or may not show up when the DB is re-opened.
+        // So we force the DB into a mode where all future writes fail.
+        RecordBackgroundError(status);
+      }
     }
     if (updates == tmp_batch_) tmp_batch_->Clear();