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Adds support for EventStream asynchronous APIs such as [S3 SelectObjectContent](https://docs.aws.amazon.com/AmazonS3/latest/API/RESTObjectSELECTContent.html). These APIs allow receiving multiple events asynchronously in the API response. These events are received by reading from a channel until that channel is closed, or the event stream is closed.

Using the S3 SelectObjectContent as an example you can read from the `Events` channel member of the `resp.EventStream` value. To interrupt the stream you can call the `resp.EventStream.Close()` method. A stream is stopped when `Close` is called, the service closes the connection on its side, or if a `Context` was used, and it is closed.

```go
resp, err := svc.SelectObjectContent(&params)
if err != nil {
    return fmt.Errorf("failed to make request, %v", err)
}
defer resp.EventStream.Close()

for event := range resp.EventStream.Events() {
    switch tv := event.(type) {
    case *s3.RecordsEvent:
         // process the selected records from the object.
         processRecords(tv.Records)
    case *StatsEvent:
         fmt.Println("Processed", *tv.Details.BytesProcessed, "bytes")
    case *s3.EndEvent:
         fmt.Println("SelectObjectContent completed")
    }
}

if err := resp.EventStream.Err(); err != nil {
    return fmt.Errorf("failed to read from API stream, %v", err)
}
```

Fix #1895
2 contributors

Users who have contributed to this file

@jasdel @jamesdbowman
118 lines (99 sloc) 3.92 KB
package aws
import (
"log"
"os"
)
// A LogLevelType defines the level logging should be performed at. Used to instruct
// the SDK which statements should be logged.
type LogLevelType uint
// LogLevel returns the pointer to a LogLevel. Should be used to workaround
// not being able to take the address of a non-composite literal.
func LogLevel(l LogLevelType) *LogLevelType {
return &l
}
// Value returns the LogLevel value or the default value LogOff if the LogLevel
// is nil. Safe to use on nil value LogLevelTypes.
func (l *LogLevelType) Value() LogLevelType {
if l != nil {
return *l
}
return LogOff
}
// Matches returns true if the v LogLevel is enabled by this LogLevel. Should be
// used with logging sub levels. Is safe to use on nil value LogLevelTypes. If
// LogLevel is nil, will default to LogOff comparison.
func (l *LogLevelType) Matches(v LogLevelType) bool {
c := l.Value()
return c&v == v
}
// AtLeast returns true if this LogLevel is at least high enough to satisfies v.
// Is safe to use on nil value LogLevelTypes. If LogLevel is nil, will default
// to LogOff comparison.
func (l *LogLevelType) AtLeast(v LogLevelType) bool {
c := l.Value()
return c >= v
}
const (
// LogOff states that no logging should be performed by the SDK. This is the
// default state of the SDK, and should be use to disable all logging.
LogOff LogLevelType = iota * 0x1000
// LogDebug state that debug output should be logged by the SDK. This should
// be used to inspect request made and responses received.
LogDebug
)
// Debug Logging Sub Levels
const (
// LogDebugWithSigning states that the SDK should log request signing and
// presigning events. This should be used to log the signing details of
// requests for debugging. Will also enable LogDebug.
LogDebugWithSigning LogLevelType = LogDebug | (1 << iota)
// LogDebugWithHTTPBody states the SDK should log HTTP request and response
// HTTP bodys in addition to the headers and path. This should be used to
// see the body content of requests and responses made while using the SDK
// Will also enable LogDebug.
LogDebugWithHTTPBody
// LogDebugWithRequestRetries states the SDK should log when service requests will
// be retried. This should be used to log when you want to log when service
// requests are being retried. Will also enable LogDebug.
LogDebugWithRequestRetries
// LogDebugWithRequestErrors states the SDK should log when service requests fail
// to build, send, validate, or unmarshal.
LogDebugWithRequestErrors
// LogDebugWithEventStreamBody states the SDK should log EventStream
// request and response bodys. This should be used to log the EventStream
// wire unmarshaled message content of requests and responses made while
// using the SDK Will also enable LogDebug.
LogDebugWithEventStreamBody
)
// A Logger is a minimalistic interface for the SDK to log messages to. Should
// be used to provide custom logging writers for the SDK to use.
type Logger interface {
Log(...interface{})
}
// A LoggerFunc is a convenience type to convert a function taking a variadic
// list of arguments and wrap it so the Logger interface can be used.
//
// Example:
// s3.New(sess, &aws.Config{Logger: aws.LoggerFunc(func(args ...interface{}) {
// fmt.Fprintln(os.Stdout, args...)
// })})
type LoggerFunc func(...interface{})
// Log calls the wrapped function with the arguments provided
func (f LoggerFunc) Log(args ...interface{}) {
f(args...)
}
// NewDefaultLogger returns a Logger which will write log messages to stdout, and
// use same formatting runes as the stdlib log.Logger
func NewDefaultLogger() Logger {
return &defaultLogger{
logger: log.New(os.Stdout, "", log.LstdFlags),
}
}
// A defaultLogger provides a minimalistic logger satisfying the Logger interface.
type defaultLogger struct {
logger *log.Logger
}
// Log logs the parameters to the stdlib logger. See log.Println.
func (l defaultLogger) Log(args ...interface{}) {
l.logger.Println(args...)
}
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