pabloem commented on a change in pull request #15996:
URL: https://github.com/apache/beam/pull/15996#discussion_r754769661
##########
File path: playground/backend/internal/code_processing/code_processing.go
##########
@@ -93,14 +105,27 @@ func Process(ctx context.Context, cacheService
cache.Cache, lc *fs_tool.LifeCycl
}
// build executor for run step
- exec = runBuilder.Build()
+ executor = runBuilder.Build()
// run
logger.Infof("%s: Run() ...\n", pipelineId)
- runCmd := exec.Run(ctxWithTimeout)
- go processCmd(runCmd, successChannel, errorChannel, dataChannel)
+ runCmd := executor.Run(ctxWithTimeout)
+
+ var runError bytes.Buffer
+ runOutput := &streaming.RunOutputWriter{Ctx: ctxWithTimeout,
CacheService: cacheService, PipelineId: pipelineId}
Review comment:
I am a little confused. I think `RunOutputWriter` fails if there has not
been any output, right? what happens at the very begining when there's no
output at all? what adds the very first output?
##########
File path: playground/backend/internal/streaming/run_output_writer.go
##########
@@ -0,0 +1,60 @@
+// Licensed to the Apache Software Foundation (ASF) under one or more
+// contributor license agreements. See the NOTICE file distributed with
+// this work for additional information regarding copyright ownership.
+// The ASF licenses this file to You under the Apache License, Version 2.0
+// (the "License"); you may not use this file except in compliance with
+// the License. You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package streaming
+
+import (
+ "beam.apache.org/playground/backend/internal/cache"
+ "context"
+ "fmt"
+ "github.com/google/uuid"
+)
+
+// RunOutputWriter is used to write the run step's output to cache as a stream.
+type RunOutputWriter struct {
+ Ctx context.Context
+ CacheService cache.Cache
+ PipelineId uuid.UUID
+}
+
+// Write writes len(p) bytes from p to cache with cache.RunOutput subKey.
+// In case some error occurs - returns (0, error).
+// In case finished with no error - returns (len(p), nil).
+//
+// As a result new bytes will be added to cache with old run output value.
+// Example:
+// p = []byte(" with new run output")
+// before Write(p): {pipelineId}:cache.RunOutput = "old run output"
+// after Write(p): {pipelineId}:cache.RunOutput = "old run output with new
run output"
+func (row *RunOutputWriter) Write(p []byte) (int, error) {
+ if len(p) == 0 {
+ return 0, nil
+ }
+
+ prevOutput, err := row.CacheService.GetValue(row.Ctx, row.PipelineId,
cache.RunOutput)
+ if err != nil {
+ return 0, err
+ }
+
+ // concat prevValue and new value
+ str := fmt.Sprintf("%s%s", prevOutput.(string), string(p))
Review comment:
it seems like redis supports an "append" operation that would save us
having to get the last value (https://redis.io/commands/append). Maybe we
should add this capability? (it's fine to leave for later)
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