README
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Logging through pipes
This functionality is needed when a parent process starts a child process and both their logs have to be collected in the parent process.
The parent process:
part, _ := pipes.NewParentPart(marshalizer)
profileReader, logsWriter := part.GetChildPipes()
command = exec.Command("child.bin")
childStdout, _:= command.StdoutPipe()
childStderr, _ := command.StderrPipe()
command.ExtraFiles = []*os.File{
...,
profileReader,
logsWriter,
}
_ = part.StartLoop(childStdout, childStderr)
StartLoop will continuously read log lines from the child (pipe logsWriter) on a separate goroutine. Child's stdout and stderr are also captured. Stdout will be logged with trace level, while stderr with error level.
Furthermore, the parent part forwards log profile changes to the child process (through pipe profileReader).
Note that the parent process is responsible to call logger.NotifyProfileChange() when it applies a new log profile (whether by sole choice or when instructed by a logviewer).
The child process
profileReader := os.NewFile(42, "/proc/self/fd/42")
logsWriter := os.NewFile(43, "/proc/self/fd/43")
part, _ := pipes.NewChildPart(profileReader, logsWriter, marshalizer)
_ = part.StartLoop()
The child process has to acquire the provided pipes, create its part of the logging dialogue and then call StartLoop.
The child part is automatically registered as observer to the global default LogOutputSubject, which means that it gets notified on each log write from any of the loggers in the process. When notified, the child part simply forwards the message (the serialized log line) to its parent, through pipe logsWriter.
Furthermore, the child part listens for eventual log profile changes on the pipe profileReader. Any profile change is applied immediately.
Documentation
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Index ¶
- Variables
- func CreateErrUnmarshalLogLine(marshalized []byte, originalErr error) error
- func NewChildPart(profileReader *os.File, logsWriter *os.File, ...) (*childPart, error)
- func NewParentPart(childName string, logLineMarshalizer logger.Marshalizer) (*parentPart, error)
- type ChildMessenger
- type Messenger
- type ParentMessenger
- type PartLoopStateType
Constants ¶
This section is empty.
Variables ¶
var ErrInvalidOperationGivenPartLoopState = errors.New("invalid operation given state of loop")
ErrInvalidOperationGivenPartLoopState signals an error
Functions ¶
func CreateErrUnmarshalLogLine ¶
CreateErrUnmarshalLogLine creates an error
func NewChildPart ¶
func NewChildPart( profileReader *os.File, logsWriter *os.File, logLineMarshalizer logger.Marshalizer, ) (*childPart, error)
NewChildPart creates a new logs sender part (in the child process)
func NewParentPart ¶
func NewParentPart(childName string, logLineMarshalizer logger.Marshalizer) (*parentPart, error)
NewParentPart creates a new logs receiver part (in the parent process)
Types ¶
type ChildMessenger ¶
type ChildMessenger struct {
Messenger
}
ChildMessenger is the messenger on child's part of the pipe
func NewChildMessenger ¶
func NewChildMessenger(profileReader *os.File, logsWriter *os.File) *ChildMessenger
NewChildMessenger creates a new messenger
func (*ChildMessenger) ReadProfile ¶
func (messenger *ChildMessenger) ReadProfile() (logger.Profile, error)
ReadProfile reads an incoming profile
func (*ChildMessenger) SendLogLine ¶
func (messenger *ChildMessenger) SendLogLine(logLineMarshalized []byte) (int, error)
SendLogLine sends a log line
type Messenger ¶
type Messenger struct {
// contains filtered or unexported fields
}
Messenger intermediates communication (message exchange) via pipes
func NewMessenger ¶
NewMessenger creates a new messenger
func (*Messenger) ReadMessage ¶
ReadMessage reads a message from the pipe Reading messages is normally performed from a single go-routine, no mutex required
type ParentMessenger ¶
type ParentMessenger struct {
Messenger
// contains filtered or unexported fields
}
ParentMessenger is the messenger on parent's part of the pipe
func NewParentMessenger ¶
func NewParentMessenger(logsReader *os.File, profileWriter *os.File, logLineMarshalizer logger.Marshalizer) *ParentMessenger
NewParentMessenger creates a new messenger
func (*ParentMessenger) ReadLogLine ¶
func (messenger *ParentMessenger) ReadLogLine() (*logger.LogLine, error)
ReadLogLine reads a log line
func (*ParentMessenger) SendProfile ¶
func (messenger *ParentMessenger) SendProfile(profile logger.Profile) error
SendProfile sends a profile
type PartLoopStateType ¶
type PartLoopStateType = uint32
PartLoopStateType represents the state of a part (parent, child) loop
const ( // PartLoopInit signals that loop hasn't been started yet PartLoopInit PartLoopStateType = iota // PartLoopRunning signals that a loop is running PartLoopRunning // PartLoopStopped signals that a loop is stopped PartLoopStopped )
Source Files