Return NotSupported in scan if IOUring not supported and enable IOUring in...

Return NotSupported in scan if IOUring not supported and enable IOUring in db_stress for async_io testing (#11197)

Summary:
- Return NotSupported in scan if IOUring not supported if async_io is enabled
- Enable IOUring in db_stress for async_io testing
- Disable async_io in circleci crash testing as circleci doesn't support IOUring

Pull Request resolved: https://github.com/facebook/rocksdb/pull/11197

Test Plan: CircleCI jobs

Reviewed By: anand1976

Differential Revision: D43096313

Pulled By: akankshamahajan15

fbshipit-source-id: c2c53a87636950c0243038b9f5bd0d91608e4fda

.circleci/config.yml

@@ -516,7 +516,7 @@ jobs:
     resource_class: large
     steps:
       - pre-steps
-      - run: ulimit -S -n `ulimit -H -n` && make V=1 -j8 CRASH_TEST_EXT_ARGS='--duration=960 --max_key=2500000' blackbox_crash_test_with_atomic_flush
+      - run: ulimit -S -n `ulimit -H -n` && make V=1 -j8 CRASH_TEST_EXT_ARGS='--duration=960 --max_key=2500000 --async_io=0' blackbox_crash_test_with_atomic_flush
       - post-steps
 
   build-linux-crashtest-tiered-storage-bb:
@@ -526,7 +526,7 @@ jobs:
       - pre-steps
       - run:
           name: "run crashtest"
-          command: ulimit -S -n `ulimit -H -n` && make V=1 -j32 CRASH_TEST_EXT_ARGS=--duration=10800 blackbox_crash_test_with_tiered_storage
+          command: ulimit -S -n `ulimit -H -n` && make V=1 -j32 CRASH_TEST_EXT_ARGS='--duration=10800 --async_io=0' blackbox_crash_test_with_tiered_storage
           no_output_timeout: 100m
       - post-steps
 
@@ -537,7 +537,7 @@ jobs:
       - pre-steps
       - run:
           name: "run crashtest"
-          command: ulimit -S -n `ulimit -H -n` && make V=1 -j32 CRASH_TEST_EXT_ARGS=--duration=10800 whitebox_crash_test_with_tiered_storage
+          command: ulimit -S -n `ulimit -H -n` && make V=1 -j32 CRASH_TEST_EXT_ARGS='--duration=10800 --async_io=0' whitebox_crash_test_with_tiered_storage
           no_output_timeout: 100m
       - post-steps
 

HISTORY.md

@@ -3,6 +3,7 @@
 
 ### Behavior changes
 * `ReadOptions::verify_checksums=false` disables checksum verification for more reads of non-`CacheEntryRole::kDataBlock` blocks.
+* In case of scan with async_io enabled, if posix doesn't support IOUring, Status::NotSupported error will be returned to the users. Initially that error was swallowed and reads were switched to synchronous reads.
 
 ### Bug Fixes
 * Fixed a data race on `ColumnFamilyData::flush_reason` caused by concurrent flushes.

db_stress_tool/db_stress_gflags.cc

@@ -1073,4 +1073,6 @@ DEFINE_uint64(stats_dump_period_sec,
               ROCKSDB_NAMESPACE::Options().stats_dump_period_sec,
               "Gap between printing stats to log in seconds");
 
+extern "C" bool RocksDbIOUringEnable() { return true; }
+
 #endif  // GFLAGS

db_stress_tool/db_stress_tool.cc

@@ -99,13 +99,6 @@ int db_stress_tool(int argc, char** argv) {
 
   env_wrapper_guard = std::make_shared<CompositeEnvWrapper>(
       raw_env, std::make_shared<DbStressFSWrapper>(raw_env->GetFileSystem()));
-  if (!env_opts) {
-    // If using the default Env (Posix), wrap DbStressEnvWrapper with the
-    // legacy EnvWrapper. This is a temporary fix for the ReadAsync interface
-    // not being properly supported with Posix and db_stress. The EnvWrapper
-    // has a default implementation of ReadAsync that redirects to Read.
-    env_wrapper_guard = std::make_shared<EnvWrapper>(env_wrapper_guard);
-  }
   db_stress_env = env_wrapper_guard.get();
 
   FLAGS_rep_factory = StringToRepFactory(FLAGS_memtablerep.c_str());

file/file_prefetch_buffer.cc

@@ -569,10 +569,11 @@ Status FilePrefetchBuffer::PrefetchAsyncInternal(
     bufs_[second].offset_ = rounddown_start2;
     assert(roundup_len2 >= chunk_len2);
     uint64_t read_len2 = static_cast<size_t>(roundup_len2 - chunk_len2);
-    Status tmp_s = ReadAsync(opts, reader, read_len2, rounddown_start2, second);
-    if (!tmp_s.ok()) {
+    s = ReadAsync(opts, reader, read_len2, rounddown_start2, second);
+    if (!s.ok()) {
       DestroyAndClearIOHandle(second);
       bufs_[second].buffer_.Clear();
+      return s;
     }
   }
 

file/prefetch_test.cc

@@ -1609,27 +1609,23 @@ TEST_P(PrefetchTest, ReadAsyncWithPosixFS) {
       num_keys++;
     }
 
-    ASSERT_EQ(num_keys, total_keys);
-    ASSERT_GT(buff_prefetch_count, 0);
-
-    // Check stats to make sure async prefetch is done.
-    {
+    if (read_async_called) {
+      ASSERT_EQ(num_keys, total_keys);
+      ASSERT_GT(buff_prefetch_count, 0);
+      // Check stats to make sure async prefetch is done.
       HistogramData async_read_bytes;
       options.statistics->histogramData(ASYNC_READ_BYTES, &async_read_bytes);
       HistogramData prefetched_bytes_discarded;
       options.statistics->histogramData(PREFETCHED_BYTES_DISCARDED,
                                         &prefetched_bytes_discarded);
-
+      ASSERT_GT(async_read_bytes.count, 0);
+      ASSERT_GT(prefetched_bytes_discarded.count, 0);
+      ASSERT_EQ(get_perf_context()->number_async_seek, 0);
+    } else {
       // Not all platforms support iouring. In that case, ReadAsync in posix
       // won't submit async requests.
-      if (read_async_called) {
-        ASSERT_GT(async_read_bytes.count, 0);
-      } else {
-        ASSERT_EQ(async_read_bytes.count, 0);
-      }
-      ASSERT_GT(prefetched_bytes_discarded.count, 0);
+      ASSERT_EQ(iter->status(), Status::NotSupported());
     }
-    ASSERT_EQ(get_perf_context()->number_async_seek, 0);
   }
 
   SyncPoint::GetInstance()->DisableProcessing();
@@ -1740,22 +1736,19 @@ TEST_P(PrefetchTest, MultipleSeekWithPosixFS) {
         num_keys++;
         iter->Next();
       }
-      ASSERT_OK(iter->status());
-      ASSERT_EQ(num_keys, num_keys_first_batch);
-      // Check stats to make sure async prefetch is done.
-      {
+
+      if (read_async_called) {
+        ASSERT_OK(iter->status());
+        ASSERT_EQ(num_keys, num_keys_first_batch);
+        // Check stats to make sure async prefetch is done.
         HistogramData async_read_bytes;
         options.statistics->histogramData(ASYNC_READ_BYTES, &async_read_bytes);
-
+        ASSERT_GT(async_read_bytes.count, 0);
+        ASSERT_GT(get_perf_context()->number_async_seek, 0);
+      } else {
         // Not all platforms support iouring. In that case, ReadAsync in posix
         // won't submit async requests.
-        if (read_async_called) {
-          ASSERT_GT(async_read_bytes.count, 0);
-          ASSERT_GT(get_perf_context()->number_async_seek, 0);
-        } else {
-          ASSERT_EQ(async_read_bytes.count, 0);
-          ASSERT_EQ(get_perf_context()->number_async_seek, 0);
-        }
+        ASSERT_EQ(iter->status(), Status::NotSupported());
       }
     }
 
@@ -1771,29 +1764,26 @@ TEST_P(PrefetchTest, MultipleSeekWithPosixFS) {
         num_keys++;
         iter->Next();
       }
-      ASSERT_OK(iter->status());
-      ASSERT_EQ(num_keys, num_keys_second_batch);
 
-      ASSERT_GT(buff_prefetch_count, 0);
+      if (read_async_called) {
+        ASSERT_OK(iter->status());
+        ASSERT_EQ(num_keys, num_keys_second_batch);
 
-      // Check stats to make sure async prefetch is done.
-      {
+        ASSERT_GT(buff_prefetch_count, 0);
+
+        // Check stats to make sure async prefetch is done.
         HistogramData async_read_bytes;
         options.statistics->histogramData(ASYNC_READ_BYTES, &async_read_bytes);
         HistogramData prefetched_bytes_discarded;
         options.statistics->histogramData(PREFETCHED_BYTES_DISCARDED,
                                           &prefetched_bytes_discarded);
-
+        ASSERT_GT(async_read_bytes.count, 0);
+        ASSERT_GT(get_perf_context()->number_async_seek, 0);
+        ASSERT_GT(prefetched_bytes_discarded.count, 0);
+      } else {
         // Not all platforms support iouring. In that case, ReadAsync in posix
         // won't submit async requests.
-        if (read_async_called) {
-          ASSERT_GT(async_read_bytes.count, 0);
-          ASSERT_GT(get_perf_context()->number_async_seek, 0);
-        } else {
-          ASSERT_EQ(async_read_bytes.count, 0);
-          ASSERT_EQ(get_perf_context()->number_async_seek, 0);
-        }
-        ASSERT_GT(prefetched_bytes_discarded.count, 0);
+        ASSERT_EQ(iter->status(), Status::NotSupported());
       }
     }
   }
@@ -1872,51 +1862,52 @@ TEST_P(PrefetchTest, SeekParallelizationTestWithPosix) {
     // Each block contains around 4 keys.
     auto iter = std::unique_ptr<Iterator>(db_->NewIterator(ro));
     iter->Seek(BuildKey(0));  // Prefetch data because of seek parallelization.
-    ASSERT_TRUE(iter->Valid());
-    iter->Next();
-    ASSERT_TRUE(iter->Valid());
-    iter->Next();
-    ASSERT_TRUE(iter->Valid());
-    iter->Next();
-    ASSERT_TRUE(iter->Valid());
+    if (std::get<1>(GetParam()) && !read_async_called) {
+      ASSERT_EQ(iter->status(), Status::NotSupported());
+    } else {
+      ASSERT_TRUE(iter->Valid());
+      iter->Next();
+      ASSERT_TRUE(iter->Valid());
+      iter->Next();
+      ASSERT_TRUE(iter->Valid());
+      iter->Next();
+      ASSERT_TRUE(iter->Valid());
 
-    // New data block. Since num_file_reads in FilePrefetch after this read is
-    // 2, it won't go for prefetching.
-    iter->Next();
-    ASSERT_TRUE(iter->Valid());
-    iter->Next();
-    ASSERT_TRUE(iter->Valid());
-    iter->Next();
-    ASSERT_TRUE(iter->Valid());
-    iter->Next();
-    ASSERT_TRUE(iter->Valid());
+      // New data block. Since num_file_reads in FilePrefetch after this read is
+      // 2, it won't go for prefetching.
+      iter->Next();
+      ASSERT_TRUE(iter->Valid());
+      iter->Next();
+      ASSERT_TRUE(iter->Valid());
+      iter->Next();
+      ASSERT_TRUE(iter->Valid());
+      iter->Next();
+      ASSERT_TRUE(iter->Valid());
 
-    // Prefetch data.
-    iter->Next();
-    ASSERT_TRUE(iter->Valid());
+      // Prefetch data.
+      iter->Next();
 
-    // Check stats to make sure async prefetch is done.
-    {
-      HistogramData async_read_bytes;
-      options.statistics->histogramData(ASYNC_READ_BYTES, &async_read_bytes);
-      // Not all platforms support iouring. In that case, ReadAsync in posix
-      // won't submit async requests.
       if (read_async_called) {
-        ASSERT_GT(async_read_bytes.count, 0);
-        ASSERT_GT(get_perf_context()->number_async_seek, 0);
-        if (std::get<1>(GetParam())) {
-          ASSERT_EQ(buff_prefetch_count, 1);
-        } else {
-          ASSERT_EQ(buff_prefetch_count, 2);
+        ASSERT_TRUE(iter->Valid());
+        // Check stats to make sure async prefetch is done.
+        {
+          HistogramData async_read_bytes;
+          options.statistics->histogramData(ASYNC_READ_BYTES,
+                                            &async_read_bytes);
+          ASSERT_GT(async_read_bytes.count, 0);
+          ASSERT_GT(get_perf_context()->number_async_seek, 0);
+          if (std::get<1>(GetParam())) {
+            ASSERT_EQ(buff_prefetch_count, 1);
+          } else {
+            ASSERT_EQ(buff_prefetch_count, 2);
+          }
         }
       } else {
-        ASSERT_EQ(async_read_bytes.count, 0);
-        ASSERT_EQ(get_perf_context()->number_async_seek, 0);
-        ASSERT_EQ(buff_prefetch_count, 1);
+        // Not all platforms support iouring. In that case, ReadAsync in posix
+        // won't submit async requests.
+        ASSERT_EQ(iter->status(), Status::NotSupported());
       }
     }
-
-    buff_prefetch_count = 0;
   }
   Close();
 }
@@ -2009,20 +2000,17 @@ TEST_P(PrefetchTest, TraceReadAsyncWithCallbackWrapper) {
     ASSERT_OK(db_->EndIOTrace());
     ASSERT_OK(env_->FileExists(trace_file_path));
 
-    ASSERT_EQ(num_keys, total_keys);
-    ASSERT_GT(buff_prefetch_count, 0);
-
-    // Check stats to make sure async prefetch is done.
-    {
+    if (read_async_called) {
+      ASSERT_EQ(num_keys, total_keys);
+      ASSERT_GT(buff_prefetch_count, 0);
+      // Check stats to make sure async prefetch is done.
       HistogramData async_read_bytes;
       options.statistics->histogramData(ASYNC_READ_BYTES, &async_read_bytes);
+      ASSERT_GT(async_read_bytes.count, 0);
+    } else {
       // Not all platforms support iouring. In that case, ReadAsync in posix
       // won't submit async requests.
-      if (read_async_called) {
-        ASSERT_GT(async_read_bytes.count, 0);
-      } else {
-        ASSERT_EQ(async_read_bytes.count, 0);
-      }
+      ASSERT_EQ(iter->status(), Status::NotSupported());
     }
 
     // Check the file to see if ReadAsync is logged.
@@ -2102,8 +2090,13 @@ TEST_F(FilePrefetchBufferTest, SeekWithBlockCacheHit) {
   // Simulate a seek of 4096 bytes at offset 0. Due to the readahead settings,
   // it will do two reads of 4096+8192 and 8192
   Status s = fpb.PrefetchAsync(IOOptions(), r.get(), 0, 4096, &result);
-  // Platforms that don't have IO uring may not support async IO
-  ASSERT_TRUE(s.IsTryAgain() || s.IsNotSupported());
+
+  // Platforms that don't have IO uring may not support async IO.
+  if (s.IsNotSupported()) {
+    return;
+  }
+
+  ASSERT_TRUE(s.IsTryAgain());
   // Simulate a block cache hit
   fpb.UpdateReadPattern(0, 4096, false);
   // Now read some data that straddles the two prefetch buffers - offset 8192 to
@@ -2137,9 +2130,13 @@ TEST_F(FilePrefetchBufferTest, NoSyncWithAsyncIO) {
   // Simulate a seek of 4000 bytes at offset 3000. Due to the readahead
   // settings, it will do two reads of 4000+4096 and 4096
   Status s = fpb.PrefetchAsync(IOOptions(), r.get(), 3000, 4000, &async_result);
+
   // Platforms that don't have IO uring may not support async IO
-  ASSERT_TRUE(s.IsTryAgain() || s.IsNotSupported());
+  if (s.IsNotSupported()) {
+    return;
+  }
 
+  ASSERT_TRUE(s.IsTryAgain());
   ASSERT_TRUE(fpb.TryReadFromCacheAsync(IOOptions(), r.get(), /*offset=*/3000,
                                         /*length=*/4000, &async_result, &s,
                                         Env::IOPriority::IO_LOW));