MDB_rxbody Struct Reference

Public Attributes
volatile txnid_t	mrb_txnid
volatile MDB_PID_T	mrb_pid
volatile MDB_THR_T	mrb_tid

Detailed Description

The information we store in a single slot of the reader table. In addition to a transaction ID, we also record the process and thread ID that owns a slot, so that we can detect stale information, e.g. threads or processes that went away without cleaning up.

Note

We currently don't check for stale records. We simply re-init the table when we know that we're the only process opening the lock file.

Member Data Documentation

mrb_pid

volatile MDB_PID_T MDB_rxbody::mrb_pid

The process ID of the process owning this reader txn.

mrb_tid

volatile MDB_THR_T MDB_rxbody::mrb_tid

The thread ID of the thread owning this txn.

mrb_txnid

volatile txnid_t MDB_rxbody::mrb_txnid

Current Transaction ID when this transaction began, or (txnid_t)-1. Multiple readers that start at the same time will probably have the same ID here. Again, it's not important to exclude them from anything; all we need to know is which version of the DB they started from so we can avoid overwriting any data used in that particular version.

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The documentation for this struct was generated from the following file:

• external/db_drivers/liblmdb/mdb.c