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KVSWrite

Purpose

Informs the Shard about a new write request, which happens in either of the following two cases:

Structure

Field Type Description
timestamp TxFingerprint the logical time at which we are writing this data.
key KVSKey the key used. With fancy hierarchical keys or suchlike, we could even specify a range of keys
datum KVSDatum option the new data to be associated with the key. No datum should only be used in a "may_write," and means don't change this value

Effects

A Shard should delay processing a KVSWrite until it has completed processing KVSAcquireLock for the same timestamp.

If the datum is None, then remove the may write marker from this timestamp in state. Any reads waiting to read what is written here must instead read from the previous write. - One way to accomplish this is to copy the previous write as a "value written" at this timestamp in state.

If datum is occupied, then remove the may write or will write marker from this timestamp in state, and record the value written at this timestamp in state.

This may trigger a KVSRead if there are any will read markers for which this timestamp is the unique previous write.

Triggers

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