Documentation
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Overview ¶
Package pubsubprotocol implements the LogDog pubsub wire protocol. This protocol wraps messages that are published to Cloud Pub/Sub for LogDog consumption.
The protocol begins with a set of header bytes to identify and parameterize the remaining data, followed by the data itself.
Note that the Pub/Sub layer is assumed to provide both a total length (so no need to length-prefix) and integrity (so no need to checksum).
Header ¶
The header is a fixed four bytes which positively identify the message as a Butler Pub/Sub message and describe the remaining data. Variant parameters can use different magic numbers to identify different parameters.
Two magic numbers are currently defined:
- 0x10 0x6d 0x06 0x00 (LogDog protocol ButlerLogBundle Raw)
- 0x10 0x6d 0x06 0x62 (LogDog protocol ButlerLogBundle GZip compressed)
Data ¶
The data component is described by the header, and consists of all data in the Pub/Sub message past the last header byte.
Index ¶
Constants ¶
const ( // DefaultCompressThreshold is the byte size threshold for compressing message // data. Messages whose byte count is less than or equal to this threshold // will not be compressed. // // This is the value used by Akamai for its compression threshold: // "The reasons 860 bytes is the minimum size for compression is twofold: // (1) The overhead of compressing an object under 860 bytes outweighs // performance gain. (2) Objects under 860 bytes can be transmitted via a // single packet anyway, so there isn't a compelling reason to compress them." DefaultCompressThreshold = 860 )
Variables ¶
This section is empty.
Functions ¶
This section is empty.
Types ¶
type Reader ¶
type Reader struct {
// Metadata is the unpacked ButlerMetadata. It is populated when the
// metadata has been read.
Metadata *logpb.ButlerMetadata
// Bundle is the unpacked ButlerLogBundle. It is populated when the
// protocol data has been read and the Metadata indicates a ButlerLogBundle
// type.
Bundle *logpb.ButlerLogBundle
// contains filtered or unexported fields
}
Reader is a protocol reader instance.
type Writer ¶
type Writer struct {
// ProtoVersion is the protocol version string to use. If empty, the current
// ProtoVersion will be used.
ProtoVersion string
// Compress, if true, allows the Writer to choose to compress data when
// applicable.
Compress bool
// CompressThreshold is the minimum size that data must be in order to
CompressThreshold int
// contains filtered or unexported fields
}
Writer writes Butler messages that the Reader can read.
Source Files