perf: allocate a mini chain's sectors for a whole write at once - #88
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francisdb wants to merge 1 commit into
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perf: allocate a mini chain's sectors for a whole write at once#88francisdb wants to merge 1 commit into
francisdb wants to merge 1 commit into
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A write allocates all the mini sectors it needs first, writes their MiniFAT entries together and grows the mini stream once, then writes through consecutive mini sectors of a regular sector in one call.
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Writing a mini stream added one mini sector at a time: a MiniFAT entry write, a second to link it, and a rewrite of the root directory entry for the mini stream's new length, per 64 bytes; the data then went in 64 bytes at a time. A write past the end of a mini chain now allocates all the mini sectors it needs first (
extend_mini_chain_by), writes the MiniFAT entries of each run of consecutive ids together, grows the mini stream (and its root entry) once, and writes through as many consecutive mini sectors as share a regular sector in one call. Reads coalesce the same way.