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Re: Concurrent Cache Pattern

by BrowserUk (Pope)
on Aug 03, 2012 at 23:55 UTC ( #985367=note: print w/replies, xml ) Need Help??

in reply to Concurrent Cache Pattern


  • Write the "answer" as a directory name at a particular place in the file system.

    Say /usr/shared/appname/cache/xxxxxx/

  • Applications reading the data simply glob the path /usr/shared/appname/cache/*.

    They get back a single name that is the answer to the question.

    If the readers need to be able to tell how fresh the answer is, they can stat the modified time.

    No locking involved.

  • The "writing" script, uses the atomic nature of rename to update the directory name at the appropriate times.

    No locking involved.

If the answer is too big to fit into a directory name, then use a file with a well-known name.

  • Readers just read the contents.
  • The writer writes updates to a different name and then deletes the original and renames.

    This requires the readers to retry if their attempts to open or read fail.

With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'
Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
"Science is about questioning the status quo. Questioning authority".
In the absence of evidence, opinion is indistinguishable from prejudice.

The start of some sanity?

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Re^2: Concurrent Cache Pattern
by pileofrogs (Priest) on Aug 07, 2012 at 20:59 UTC

    This is an awesome answer. Exactly what I was hoping for.

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