1 files changed, 344 insertions, 0 deletions
diff --git a/src/rocksdb/db/error_handler.cc b/src/rocksdb/db/error_handler.cc
new file mode 100644
index 000000000..3ba4d9fd9
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+++ b/src/rocksdb/db/error_handler.cc
@@ -0,0 +1,344 @@
+//  Copyright (c) 2018-present, Facebook, Inc.  All rights reserved.
+//  This source code is licensed under both the GPLv2 (found in the
+//  COPYING file in the root directory) and Apache 2.0 License
+//  (found in the LICENSE.Apache file in the root directory).
+//
+#include "db/error_handler.h"
+#include "db/db_impl/db_impl.h"
+#include "db/event_helpers.h"
+#include "file/sst_file_manager_impl.h"
+
+namespace ROCKSDB_NAMESPACE {
+
+// Maps to help decide the severity of an error based on the
+// BackgroundErrorReason, Code, SubCode and whether db_options.paranoid_checks
+// is set or not. There are 3 maps, going from most specific to least specific
+// (i.e from all 4 fields in a tuple to only the BackgroundErrorReason and
+// paranoid_checks). The less specific map serves as a catch all in case we miss
+// a specific error code or subcode.
+std::map<std::tuple<BackgroundErrorReason, Status::Code, Status::SubCode, bool>,
+         Status::Severity>
+    ErrorSeverityMap = {
+        // Errors during BG compaction
+        {std::make_tuple(BackgroundErrorReason::kCompaction,
+                         Status::Code::kIOError, Status::SubCode::kNoSpace,
+                         true),
+         Status::Severity::kSoftError},
+        {std::make_tuple(BackgroundErrorReason::kCompaction,
+                         Status::Code::kIOError, Status::SubCode::kNoSpace,
+                         false),
+         Status::Severity::kNoError},
+        {std::make_tuple(BackgroundErrorReason::kCompaction,
+                         Status::Code::kIOError, Status::SubCode::kSpaceLimit,
+                         true),
+         Status::Severity::kHardError},
+        // Errors during BG flush
+        {std::make_tuple(BackgroundErrorReason::kFlush, Status::Code::kIOError,
+                         Status::SubCode::kNoSpace, true),
+         Status::Severity::kHardError},
+        {std::make_tuple(BackgroundErrorReason::kFlush, Status::Code::kIOError,
+                         Status::SubCode::kNoSpace, false),
+         Status::Severity::kNoError},
+        {std::make_tuple(BackgroundErrorReason::kFlush, Status::Code::kIOError,
+                         Status::SubCode::kSpaceLimit, true),
+         Status::Severity::kHardError},
+        // Errors during Write
+        {std::make_tuple(BackgroundErrorReason::kWriteCallback,
+                         Status::Code::kIOError, Status::SubCode::kNoSpace,
+                         true),
+         Status::Severity::kHardError},
+        {std::make_tuple(BackgroundErrorReason::kWriteCallback,
+                         Status::Code::kIOError, Status::SubCode::kNoSpace,
+                         false),
+         Status::Severity::kHardError},
+};
+
+std::map<std::tuple<BackgroundErrorReason, Status::Code, bool>, Status::Severity>
+    DefaultErrorSeverityMap = {
+        // Errors during BG compaction
+        {std::make_tuple(BackgroundErrorReason::kCompaction,
+                         Status::Code::kCorruption, true),
+         Status::Severity::kUnrecoverableError},
+        {std::make_tuple(BackgroundErrorReason::kCompaction,
+                         Status::Code::kCorruption, false),
+         Status::Severity::kNoError},
+        {std::make_tuple(BackgroundErrorReason::kCompaction,
+                         Status::Code::kIOError, true),
+         Status::Severity::kFatalError},
+        {std::make_tuple(BackgroundErrorReason::kCompaction,
+                         Status::Code::kIOError, false),
+         Status::Severity::kNoError},
+        // Errors during BG flush
+        {std::make_tuple(BackgroundErrorReason::kFlush,
+                         Status::Code::kCorruption, true),
+         Status::Severity::kUnrecoverableError},
+        {std::make_tuple(BackgroundErrorReason::kFlush,
+                         Status::Code::kCorruption, false),
+         Status::Severity::kNoError},
+        {std::make_tuple(BackgroundErrorReason::kFlush,
+                         Status::Code::kIOError, true),
+         Status::Severity::kFatalError},
+        {std::make_tuple(BackgroundErrorReason::kFlush,
+                         Status::Code::kIOError, false),
+         Status::Severity::kNoError},
+        // Errors during Write
+        {std::make_tuple(BackgroundErrorReason::kWriteCallback,
+                         Status::Code::kCorruption, true),
+         Status::Severity::kUnrecoverableError},
+        {std::make_tuple(BackgroundErrorReason::kWriteCallback,
+                         Status::Code::kCorruption, false),
+         Status::Severity::kNoError},
+        {std::make_tuple(BackgroundErrorReason::kWriteCallback,
+                         Status::Code::kIOError, true),
+         Status::Severity::kFatalError},
+        {std::make_tuple(BackgroundErrorReason::kWriteCallback,
+                         Status::Code::kIOError, false),
+         Status::Severity::kNoError},
+};
+
+std::map<std::tuple<BackgroundErrorReason, bool>, Status::Severity>
+    DefaultReasonMap = {
+        // Errors during BG compaction
+        {std::make_tuple(BackgroundErrorReason::kCompaction, true),
+          Status::Severity::kFatalError},
+        {std::make_tuple(BackgroundErrorReason::kCompaction, false),
+          Status::Severity::kNoError},
+        // Errors during BG flush
+        {std::make_tuple(BackgroundErrorReason::kFlush, true),
+          Status::Severity::kFatalError},
+        {std::make_tuple(BackgroundErrorReason::kFlush, false),
+          Status::Severity::kNoError},
+        // Errors during Write
+        {std::make_tuple(BackgroundErrorReason::kWriteCallback, true),
+          Status::Severity::kFatalError},
+        {std::make_tuple(BackgroundErrorReason::kWriteCallback, false),
+          Status::Severity::kFatalError},
+        // Errors during Memtable update
+        {std::make_tuple(BackgroundErrorReason::kMemTable, true),
+          Status::Severity::kFatalError},
+        {std::make_tuple(BackgroundErrorReason::kMemTable, false),
+          Status::Severity::kFatalError},
+};
+
+void ErrorHandler::CancelErrorRecovery() {
+#ifndef ROCKSDB_LITE
+  db_mutex_->AssertHeld();
+
+  // We'll release the lock before calling sfm, so make sure no new
+  // recovery gets scheduled at that point
+  auto_recovery_ = false;
+  SstFileManagerImpl* sfm = reinterpret_cast<SstFileManagerImpl*>(
+      db_options_.sst_file_manager.get());
+  if (sfm) {
+    // This may or may not cancel a pending recovery
+    db_mutex_->Unlock();
+    bool cancelled = sfm->CancelErrorRecovery(this);
+    db_mutex_->Lock();
+    if (cancelled) {
+      recovery_in_prog_ = false;
+    }
+  }
+#endif
+}
+
+// This is the main function for looking at an error during a background
+// operation and deciding the severity, and error recovery strategy. The high
+// level algorithm is as follows -
+// 1. Classify the severity of the error based on the ErrorSeverityMap,
+//    DefaultErrorSeverityMap and DefaultReasonMap defined earlier
+// 2. Call a Status code specific override function to adjust the severity
+//    if needed. The reason for this is our ability to recover may depend on
+//    the exact options enabled in DBOptions
+// 3. Determine if auto recovery is possible. A listener notification callback
+//    is called, which can disable the auto recovery even if we decide its
+//    feasible
+// 4. For Status::NoSpace() errors, rely on SstFileManagerImpl to control
+//    the actual recovery. If no sst file manager is specified in DBOptions,
+//    a default one is allocated during DB::Open(), so there will always be
+//    one.
+// This can also get called as part of a recovery operation. In that case, we
+// also track the error separately in recovery_error_ so we can tell in the
+// end whether recovery succeeded or not
+Status ErrorHandler::SetBGError(const Status& bg_err, BackgroundErrorReason reason) {
+  db_mutex_->AssertHeld();
+
+  if (bg_err.ok()) {
+    return Status::OK();
+  }
+
+  bool paranoid = db_options_.paranoid_checks;
+  Status::Severity sev = Status::Severity::kFatalError;
+  Status new_bg_err;
+  bool found = false;
+
+  {
+    auto entry = ErrorSeverityMap.find(std::make_tuple(reason, bg_err.code(),
+          bg_err.subcode(), paranoid));
+    if (entry != ErrorSeverityMap.end()) {
+      sev = entry->second;
+      found = true;
+    }
+  }
+
+  if (!found) {
+    auto entry = DefaultErrorSeverityMap.find(std::make_tuple(reason,
+          bg_err.code(), paranoid));
+    if (entry != DefaultErrorSeverityMap.end()) {
+      sev = entry->second;
+      found = true;
+    }
+  }
+
+  if (!found) {
+    auto entry = DefaultReasonMap.find(std::make_tuple(reason, paranoid));
+    if (entry != DefaultReasonMap.end()) {
+      sev = entry->second;
+    }
+  }
+
+  new_bg_err = Status(bg_err, sev);
+
+  // Check if recovery is currently in progress. If it is, we will save this
+  // error so we can check it at the end to see if recovery succeeded or not
+  if (recovery_in_prog_ && recovery_error_.ok()) {
+    recovery_error_ = new_bg_err;
+  }
+
+  bool auto_recovery = auto_recovery_;
+  if (new_bg_err.severity() >= Status::Severity::kFatalError && auto_recovery) {
+    auto_recovery = false;
+  }
+
+  // Allow some error specific overrides
+  if (new_bg_err == Status::NoSpace()) {
+    new_bg_err = OverrideNoSpaceError(new_bg_err, &auto_recovery);
+  }
+
+  if (!new_bg_err.ok()) {
+    Status s = new_bg_err;
+    EventHelpers::NotifyOnBackgroundError(db_options_.listeners, reason, &s,
+                                          db_mutex_, &auto_recovery);
+    if (!s.ok() && (s.severity() > bg_error_.severity())) {
+      bg_error_ = s;
+    } else {
+      // This error is less severe than previously encountered error. Don't
+      // take any further action
+      return bg_error_;
+    }
+  }
+
+  if (auto_recovery) {
+    recovery_in_prog_ = true;
+
+    // Kick-off error specific recovery
+    if (bg_error_ == Status::NoSpace()) {
+      RecoverFromNoSpace();
+    }
+  }
+  return bg_error_;
+}
+
+Status ErrorHandler::OverrideNoSpaceError(Status bg_error,
+                                          bool* auto_recovery) {
+#ifndef ROCKSDB_LITE
+  if (bg_error.severity() >= Status::Severity::kFatalError) {
+    return bg_error;
+  }
+
+  if (db_options_.sst_file_manager.get() == nullptr) {
+    // We rely on SFM to poll for enough disk space and recover
+    *auto_recovery = false;
+    return bg_error;
+  }
+
+  if (db_options_.allow_2pc &&
+      (bg_error.severity() <= Status::Severity::kSoftError)) {
+    // Don't know how to recover, as the contents of the current WAL file may
+    // be inconsistent, and it may be needed for 2PC. If 2PC is not enabled,
+    // we can just flush the memtable and discard the log
+    *auto_recovery = false;
+    return Status(bg_error, Status::Severity::kFatalError);
+  }
+
+  {
+    uint64_t free_space;
+    if (db_options_.env->GetFreeSpace(db_options_.db_paths[0].path,
+                                      &free_space) == Status::NotSupported()) {
+      *auto_recovery = false;
+    }
+  }
+
+  return bg_error;
+#else
+  (void)auto_recovery;
+  return Status(bg_error, Status::Severity::kFatalError);
+#endif
+}
+
+void ErrorHandler::RecoverFromNoSpace() {
+#ifndef ROCKSDB_LITE
+  SstFileManagerImpl* sfm =
+      reinterpret_cast<SstFileManagerImpl*>(db_options_.sst_file_manager.get());
+
+  // Inform SFM of the error, so it can kick-off the recovery
+  if (sfm) {
+    sfm->StartErrorRecovery(this, bg_error_);
+  }
+#endif
+}
+
+Status ErrorHandler::ClearBGError() {
+#ifndef ROCKSDB_LITE
+  db_mutex_->AssertHeld();
+
+  // Signal that recovery succeeded
+  if (recovery_error_.ok()) {
+    Status old_bg_error = bg_error_;
+    bg_error_ = Status::OK();
+    recovery_in_prog_ = false;
+    EventHelpers::NotifyOnErrorRecoveryCompleted(db_options_.listeners,
+                                                 old_bg_error, db_mutex_);
+  }
+  return recovery_error_;
+#else
+  return bg_error_;
+#endif
+}
+
+Status ErrorHandler::RecoverFromBGError(bool is_manual) {
+#ifndef ROCKSDB_LITE
+  InstrumentedMutexLock l(db_mutex_);
+  if (is_manual) {
+    // If its a manual recovery and there's a background recovery in progress
+    // return busy status
+    if (recovery_in_prog_) {
+      return Status::Busy();
+    }
+    recovery_in_prog_ = true;
+  }
+
+  if (bg_error_.severity() == Status::Severity::kSoftError) {
+    // Simply clear the background error and return
+    recovery_error_ = Status::OK();
+    return ClearBGError();
+  }
+
+  // Reset recovery_error_. We will use this to record any errors that happen
+  // during the recovery process. While recovering, the only operations that
+  // can generate background errors should be the flush operations
+  recovery_error_ = Status::OK();
+  Status s = db_->ResumeImpl();
+  // For manual recover, shutdown, and fatal error  cases, set
+  // recovery_in_prog_ to false. For automatic background recovery, leave it
+  // as is regardless of success or failure as it will be retried
+  if (is_manual || s.IsShutdownInProgress() ||
+      bg_error_.severity() >= Status::Severity::kFatalError) {
+    recovery_in_prog_ = false;
+  }
+  return s;
+#else
+  (void)is_manual;
+  return bg_error_;
+#endif
+}
+}  // namespace ROCKSDB_NAMESPACE