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| <h4 class="subsection">24.4.7 Atomic Data Access and Signal Handling</h4> |
| |
| <p>Whether the data in your application concerns atoms, or mere text, you |
| have to be careful about the fact that access to a single datum is not |
| necessarily <dfn>atomic</dfn>. This means that it can take more than one |
| instruction to read or write a single object. In such cases, a signal |
| handler might be invoked in the middle of reading or writing the object. |
| |
| <p>There are three ways you can cope with this problem. You can use data |
| types that are always accessed atomically; you can carefully arrange |
| that nothing untoward happens if an access is interrupted, or you can |
| block all signals around any access that had better not be interrupted |
| (see <a href="Blocking-Signals.html#Blocking-Signals">Blocking Signals</a>). |
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| <li><a accesskey="1" href="Non_002datomic-Example.html#Non_002datomic-Example">Non-atomic Example</a>: A program illustrating interrupted access. |
| <li><a accesskey="2" href="Atomic-Types.html#Atomic-Types">Types</a>: Data types that guarantee no interruption. |
| <li><a accesskey="3" href="Atomic-Usage.html#Atomic-Usage">Usage</a>: Proving that interruption is harmless. |
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