Writing values to a shared memory segment¶
write_shared_memory() |
Writing values to shared memory |
SYNTAX
write_shared_memory(shm_id, offset, len, options)
Writes the current field values from the associated record buffer into the shared memory segment specified in shm_id . Sculptor ensures that this operation is atomic so that other programs cannot read a partly updated record.
The associated record buffer was specified in the function call that created or linked to the segment.
shm_id |
The return value from the function that created or linked to the segment. |
offset |
The byte offset within the record to start writing from. This feature is for advanced use, and should normally be set to 0. |
len |
The number of bytes to write. This feature is for advanced use. Set to 0 to write the entire record. |
options |
May be SHM_KEEP_LOCK or 0. If options is SHM_KEEP_LOCK, Sculptor prevents other programs writing to the shared memory segment until this program calls write_shared_memory() or read_shared_memory() with options = 0, or calls unlock_shared_memory(). It is very important to hold this lock for a short time only since, when it is set, other programs that try to access this memory segment will go into a non-responding state. |
The function returns the number of bytes written.
Shared memory functions |
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Create a shared memory segment |
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Link to an existing shared memory segment |
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Read the current field values from shared memory into associated record buffer |
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Write the current values from associated record buffer into shared memory |
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Unlock a shared memory segment |
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Unlink a program from a shared memory segment |
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RELATED TOPICS |