Branch free parse digits - Githubissues

eclipse-vertx / vertx-sql-client

High performance reactive SQL Client written in Java

Apache License 2.0

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Branch free parse digits #1432

Open franz1981 opened 3 months ago

franz1981 commented 3 months ago

It contains 3 improvements (unfinished):

O(1) collation lookup table
branchless/batchy parse digits
NOT YET STARTED: https://github.com/eclipse-vertx/vertx-sql-client/blob/9073da6171b7688a7491398522dcb6c454bd5960/vertx-mysql-client/src/main/java/io/vertx/mysqlclient/impl/datatype/DataTypeCodec.java#L61 exceed MinJumpTableSize (see https://stackoverflow.com/questions/44988841/force-tableswitch-instead-of-lookupswitch for more info): we should find a way to reduce the number of branches here or find a different way to perform it, because the branch predictor AND the JIT doesn't enjoy it

franz1981 commented 3 months ago

Some of the proposed improvements are coming from https://github.com/cescoffier/fortune-benchmark/tree/main/fortune-reactive-mariadb/src/main/java/me/escoffier/fortune/reactive/mariadb so IMO they are not actually so valid (eg the cost of decoding in digits) , but given that I was having fun reading a nice article on it I said "why not trying implementing it?"