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CHANGES.md

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CHANGES

To track changes in the protocol, or defaults, rather than differences in any particular implementation

Chronicle Queue v5

  • FAST_XXX RollSchemes see https://github.com/OpenHFT/Chronicle-Queue/blob/ea/src/main/java/net/openhft/chronicle/queue/RollCycles.java

  • Default RollScheme (e.g. for SingleChronicleQueueBuilder) changes from DAILY to FAST_DAILY

  • Since schemes make reduced bits available for cycle value, new concept of "epoch" which appears to be a constant offset to the cycle value, ie. we now longer assume epoch is midnight 1970.01.01

  • New per-queue metadata.cq4t file replaces directory-listing.cq4t file.

    • STStore -> SCQMeta -> SCQSRoll fields need to be parsed since they are removed from queue files:
    • length (uint32)
    • epoch (uint8)
    • format (text)

  • queue metatdata wire encoder changes:

    • SCQSIndexing.indexSpacing changes from uint8 to uint16

  • a v5 queue with no data written can be a metadata.cq4t with no queue files (relax queuefile existance checks)

  • SingleChronicleQueueBuilder writeText() seems to be writing a one-byte prefix to the data

  • data/metadata messages are now 4 byte aligned (see pad4 in parse_queue_block) so the header CAS read is always aligned

  • only appenders can write metadata and index pages (no lazy indexing - libchronicle never supported it)

Chronicle Queue v4

  • requires at least one queuefile to learn the roll scheme, although we do not know what the rollscheme is to find the queuefile, so bootstrap using filesystem glob
  • queue data/metadata pages are not aligned