memory.go

package buffer

import (
	"fmt"

	"github.com/Jeffail/benthos/v3/internal/docs"
	"github.com/Jeffail/benthos/v3/lib/buffer/parallel"
	"github.com/Jeffail/benthos/v3/lib/log"
	"github.com/Jeffail/benthos/v3/lib/message/batch"
	"github.com/Jeffail/benthos/v3/lib/metrics"
	"github.com/Jeffail/benthos/v3/lib/types"
)

//------------------------------------------------------------------------------

func init() {
	Constructors[TypeMemory] = TypeSpec{
		constructor: NewMemory,
		Summary: `
Stores consumed messages in memory and acknowledges them at the input level.
During shutdown Benthos will make a best attempt at flushing all remaining
messages before exiting cleanly.`,
		Description: `
This buffer is appropriate when consuming messages from inputs that do not
gracefully handle back pressure and where delivery guarantees aren't critical.

This buffer has a configurable limit, where consumption will be stopped with
back pressure upstream if the total size of messages in the buffer reaches this
amount. Since this calculation is only an estimate, and the real size of
messages in RAM is always higher, it is recommended to set the limit
significantly below the amount of RAM available.

### Batching

It is possible to batch up messages sent from this buffer using a
[batch policy](/docs/configuration/batching#batch-policy).`,
		FieldSpecs: docs.FieldSpecs{
			docs.FieldCommon("limit", "The maximum buffer size (in bytes) to allow before applying backpressure upstream."),
			docs.FieldCommon("batch_policy", "Optionally configure a policy to flush buffered messages in batches.").WithChildren(
				append(docs.FieldSpecs{
					docs.FieldCommon("enabled", "Whether to batch messages as they are flushed."),
				}, batch.FieldSpec().Children...)...,
			),
		},
		sanitiseConfigFunc: func(conf Config) (interface{}, error) {
			bSanit, err := batch.SanitisePolicyConfig(batch.PolicyConfig(conf.Memory.BatchPolicy.PolicyConfig))
			if err != nil {
				return nil, err
			}
			if bSanitObj, ok := bSanit.(map[string]interface{}); ok {
				bSanitObj["enabled"] = conf.Memory.BatchPolicy.Enabled
			}
			return map[string]interface{}{
				"limit":        conf.Memory.Limit,
				"batch_policy": bSanit,
			}, nil
		},
	}
}

//------------------------------------------------------------------------------

// EnabledBatchPolicyConfig is a batch.PolicyConfig with an enable field.
type EnabledBatchPolicyConfig struct {
	Enabled            bool `json:"enabled" yaml:"enabled"`
	batch.PolicyConfig `json:",inline" yaml:",inline"`
}

// MemoryConfig is config values for a purely memory based ring buffer type.
type MemoryConfig struct {
	Limit       int                      `json:"limit" yaml:"limit"`
	BatchPolicy EnabledBatchPolicyConfig `json:"batch_policy" yaml:"batch_policy"`
}

// NewMemoryConfig creates a new MemoryConfig with default values.
func NewMemoryConfig() MemoryConfig {
	return MemoryConfig{
		Limit: 1024 * 1024 * 500, // 500MB
		BatchPolicy: EnabledBatchPolicyConfig{
			Enabled:      false,
			PolicyConfig: batch.NewPolicyConfig(),
		},
	}
}

//------------------------------------------------------------------------------

// NewMemory creates a buffer held in memory.
func NewMemory(config Config, mgr types.Manager, log log.Modular, stats metrics.Type) (Type, error) {
	wrap := NewParallelWrapper(config, parallel.NewMemory(config.Memory.Limit), log, stats)
	if !config.Memory.BatchPolicy.Enabled {
		return wrap, nil
	}
	pol, err := batch.NewPolicy(config.Memory.BatchPolicy.PolicyConfig, mgr, log, stats)
	if err != nil {
		return nil, fmt.Errorf("batch policy config error: %v", err)
	}
	return NewParallelBatcher(pol, wrap, log, stats), nil
}

//------------------------------------------------------------------------------