Method compress_entry

src/borg/cache.py:418–439

compress a files cache entry: - use the ChunkIndex to "compress" the entry's chunks list (256bit key + 32bit size -> 32bit index). - use msgpack to pack the entry (reduce memory usage by packing and having less python objects). Note: the result is only valid while

(self, entry)

        self.start_backup = start_backup

    def compress_entry(self, entry):
        """
        compress a files cache entry:

        - use the ChunkIndex to "compress" the entry's chunks list (256bit key + 32bit size -> 32bit index).
        - use msgpack to pack the entry (reduce memory usage by packing and having less python objects).

        Note: the result is only valid while the ChunkIndex is in memory!
        """
        assert isinstance(self.chunks, ChunkIndex), f"{self.chunks} is not a ChunkIndex"
        assert isinstance(entry, FileCacheEntry)
        compressed_chunks = []
        for id, size in entry.chunks:
            cie = self.chunks[id]  # may raise KeyError if chunk id is not in repo
            if cie.size == 0:  # size is not known in the chunks index yet
                self.chunks[id] = cie._replace(size=size)
            else:
                assert size == cie.size, f"{size} != {cie.size}"
            idx = self.chunks.k_to_idx(id)
            compressed_chunks.append(idx)
        entry = entry._replace(chunks=compressed_chunks)
        return msgpack.packb(entry)

    def decompress_entry(self, entry_packed):
        """reverse operation of compress_entry"""