1. David Young
  2. vchoi_fork

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     It first creates one 3d dataset using chunked storage, each chunk is a (1,
 
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1. Title:
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     User Guide for SWMR Use Case Programs
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​
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2. Purpose:
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     This is a User Guide of the SWMR Use Case programs. It descibes the use
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    case program and explain how to run them.
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​
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2.1. Author and Dates:
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     Version 2: By Albert Cheng (acheng@hdfgroup.org), 2013/06/18.
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     Version 1: By Albert Cheng (acheng@hdfgroup.org), 2013/06/01.
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​
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​
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%%%%Use Case 1.7%%%%
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3. Use Case [1.7]:
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     Appending a single chunk
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​
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3.1. Program name:
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     use_append_chunk
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​
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3.2. Description:
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     Appending a single chunk of raw data to a dataset along an unlimited
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     dimension within a pre-created file and reading the new data back.
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​
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     It first creates one 3d dataset using chunked storage, each chunk
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     is a (1, chunksize, chunksize) square.  The dataset is (unlimited,
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     chunksize, chunksize). Data type is 2 bytes integer.  It starts out
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     "empty", i.e., first dimension is 0.
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​
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     The writer then appends planes, each of (1,chunksize,chunksize)
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     to the dataset. Fills each plan with plane number and then writes
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     it at the nth plane. Increases the plane number and repeats till
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     the end of dataset, when it reaches chunksize long. End product is
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     a chunksize^3 cube.
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​
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     The reader is a separated process, running in parallel with
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     the writer.  It reads planes from the dataset.  It expects the
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     dataset is being changed (growing). It checks the unlimited dimension
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     (dimension[0]). When it increases, it will read in the new planes, one
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     by one, and verify the data correctness.  (The nth plan should contain
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     all "n".) When the unlimited dimension grows to the chunksize (it
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     becomes a cube), that is the expected end of data, the reader exits.
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​
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3.3. How to run the program:
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     Simplest way is
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     $ use_append_chunk
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​
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     It creates a skeleton dataset (0,256,256) of shorts. Then fork off
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     a process, which becomes the reader process to read planes from the
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     dataset, while the original process continues as the writer process
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     to append planes onto the dataset.