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Viewing changes to plugin/transaction_log/module.cc

Adds a vector of write buffers to the transaction log applier
object.  This eliminates the calls to malloc() for writing
most transaction log entries (the only calls to malloc() will
be when an existing write buffer is not large enough).  

There is a configuration setting now for the number of write
buffers to create on startup.  The slot algorithm is a simple
modulo on the session ID.

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Lines of Context:
plugin/transaction_log/module.cc
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 * in truncating the log file. 
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 */
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static bool sysvar_transaction_log_truncate_debug= false;
 
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/**
 
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 * The name of the main transaction log file on disk.  With no prefix,
 
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 * this goes into Drizzle's $datadir.
 
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 */
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static const char DEFAULT_LOG_FILE_PATH[]= "transaction.log"; /* In datadir... */
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/** 
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 * Transaction Log plugin system variable - Should we write a CRC32 checksum for 
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 * TransactionLog::SYNC_METHOD_EVERY_SECOND == 2  ... sync at most once a second
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 */
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static uint32_t sysvar_transaction_log_sync_method= 0;
 
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/**
 
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 * Transaction Log plugin system variable - Number of slots to create
 
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 * for managing write buffers
 
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 */
 
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static uint32_t sysvar_transaction_log_num_write_buffers= 8;
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/** DATA_DICTIONARY views */
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static TransactionLogTool *transaction_log_tool;
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  if (sysvar_transaction_log_enabled)
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  {
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    transaction_log= new (nothrow) TransactionLog(string(sysvar_transaction_log_file),
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                                                  sysvar_transaction_log_sync_method);
 
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                                                  sysvar_transaction_log_sync_method,
 
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                                                  sysvar_transaction_log_checksum_enabled);
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    if (transaction_log == NULL)
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    {
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    /* Create the applier plugin and register it */
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    transaction_log_applier= new (nothrow) TransactionLogApplier("transaction_log_applier",
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                                                                 *transaction_log, 
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                                                                 sysvar_transaction_log_checksum_enabled);
 
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                                                                 sysvar_transaction_log_num_write_buffers);
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    if (transaction_log_applier == NULL)
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    {
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      errmsg_printf(ERRMSG_LVL_ERROR, _("Failed to allocate the TransactionLogApplier instance.  Got error: %s\n"), 
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                           set_truncate_debug, /* update func */
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                           false /* default */);
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static DRIZZLE_SYSVAR_STR(log_file,
 
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static DRIZZLE_SYSVAR_STR(file,
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                          sysvar_transaction_log_file,
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                          PLUGIN_VAR_READONLY,
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                          N_("Path to the file to use for transaction log"),
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                           2,
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                           0);
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static DRIZZLE_SYSVAR_UINT(num_write_buffers,
 
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                           sysvar_transaction_log_num_write_buffers,
 
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                           PLUGIN_VAR_OPCMDARG,
 
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                           N_("Number of slots for in-memory write buffers (default=8)."),
 
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                           NULL, /* check func */
 
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                           NULL, /* update func */
 
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                           8, /* default */
 
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                           4,
 
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                           8192,
 
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                           0);
 
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static drizzle_sys_var* sys_variables[]= {
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  DRIZZLE_SYSVAR(enable),
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  DRIZZLE_SYSVAR(truncate_debug),
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  DRIZZLE_SYSVAR(log_file),
 
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  DRIZZLE_SYSVAR(file),
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  DRIZZLE_SYSVAR(enable_checksum),
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  DRIZZLE_SYSVAR(sync_method),
 
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  DRIZZLE_SYSVAR(num_write_buffers),
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  NULL
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};
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