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Diffstat (limited to 'note')
| -rw-r--r-- | note | 141 |
1 files changed, 141 insertions, 0 deletions
@@ -0,0 +1,141 @@ +write_transaction or stmt +one way get the cache length and then gtid length and then last event (mostly +query log event) and add them up and save into gtid packet +second way no calculation relie on actual binlog event writen in cache and then +write it into gtid event (fuck it wont work , what about fucking fsync and +i have to call write agian really bad idea) +so what the fuck to do +plan so far +we will be giing wia first method since secind meyhod will not work +there are three type if events one with comit one wi rollback and xid log event +so query log dvent and xid xheexkpoint eveent +it shhould be eastt yo get datta size from xid log but for qury we n3d to +do some shit. +one option mite bee to use fjxed length since there are onlyb2 options +for the time this is the the only solutiin --- asshole this wont work + +So the plan right now +write_transaction_or_stmt +1. Rememember the current posiotion in cache (thread trx/stmt cache) (in case of +rollback and commit only , Xid event will have fixed lenght), why the not genneralize +it ? +2. write the event in cache(IO_CACHE) (how the fuck I will be doing i t, no clue) +3.read the whole cache length , trx and stmt +4 Pass it to write_gtid_event + +::write() +No fucking clue +here babe + { + 5984 Log_event_writer writer(&cache_data->cache_log, cache_data); + 5985 + 5986 /* + 5987 ┆ Write pending event to the cache. + 5988 */ + 5989 DBUG_EXECUTE_IF("simulate_disk_full_at_flush_pending", + 5990 ┆ ┆ ┆ ┆ {DBUG_SET("+d,simulate_file_write_error");}); + 5991 if (writer.write(pending)) + 5992 } + +DDL +fuck me + +So now for the writing in gtid_log_event +We will have the size of transaction - gtid_event_size +On the time of write , We need to have one flag +But how ? I mean we just have +bro i just explained that in #replication channel +see there +in shorrt extendable one byte flag every time when we over shoot +how to store thread id 4bytes +how we will be storing transaction size maybe use net_write_packet or 8 solid bytes + +FOR THE TIME LETS HAVE 8 +4 no flexible , we will change it later + + + + + + + + +Circular buffer + +Memeber variables + uchar* buffer; + uchar* buffer_end; + uint64 size; + uint elements; + /* + Some time we can have empty space in end if transaction/event is big to fit + in continues space. + */ + uchar* buffer_usable_ptr; + // Actual free space + uint64 usable_free_space; + uchar* write_head; + uchar* read_head; + uchar* flush_head; + std::mutex read_lock; + std::mutex write_lock; + +Empty space for this case +S= Buffer_start +F= Flush Pointer +W= write pointer +E= buffer end +U= Buffer usable_ptr + +if this case +S--F----W-----E +E - W + F -S + +if this case +S--W-- F --- U--E +F-W + + +Write code +TS = Transaction size + +if this case +S--F----W----E +if E-W > TS +then write data and W+= TS + +if E-W < TS +buffer_usable_ptr= write_head +write_head= 0 +It will become the second case + + +if this case +S--W----F--U--E +if TS < F -W +write +W+= TS +else + give error that buffer is full +and write into file + +Read from queue + R < W +S--R---W--E + +lock the mutex +R+= TS/ES +unlock the mutex +return the old read ptr + +R > W +S--W---R--U--E +lock the mutex +R += TS/ES +if R == U +R= 0 +unlock the mutex +return the old ptr + + + +Bharthi no 02024407100 vandna mam |