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Add backend examples

Signed-off-by: Vicent Marti <>
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vmg committed Dec 9, 2010
1 parent 187d06b commit a4602c0d658765c41d889c161822d6c0ec8059fe
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  1. +25 −0 api.html
@@ -673,6 +673,17 @@ <h3 id="indexread">Implementing a custom backend</h3>
it to an existing object database using the <code>git_odb_add_backend(backend)</code> method.
A single backend instance can only be active in one ODB at the same time</p>
+ <p>The <code>priority</code> field is used to when sorting the backends for their usage:
+ for instance, a <code>read</code> call on the ODB will first check the backend with the
+ highest priority and attempt to read the object from it; if the backend returns an error
+ code, it will fallback silently to the following backend, until the object has been read
+ or there are no more backends left.</p>
+ <p>It it not necessary to specify all the backend methods on a custom backend: unspecified
+ methods will be skipped silently on their respective backend calls. If no <code>free</code>
+ method is specified for a given backend, the library will automatically try to free the backend using
+ a plain <code>free()</code> call.</p>
<span class="shtitle">Ruby</span>
<pre class="sh_ruby">
class TestBackend &lt; Rugged::Backend
@@ -702,6 +713,20 @@ <h3 id="indexread">Implementing a custom backend</h3>
+ <h3 id="indexread">A world of possibilities</h3>
+<p>The options when implementing custom backends are endless. Here are just a few examples:</p>
+ <ul>
+ <li>in-memory object storage (useful for config storage)</li>
+ <li>in-memory cache for fast lookups (make sure you write the objects back to disk before flushing the cache!)</li>
+ <li>a transparent backend acting as a logger for all the ODB reads and writes</li>
+ <li>SQLite backend writing and reading objects from a compact database</li>
+ <li>Cassandra backend (or your favourite NoSQL flavour!)</li>
+ <li>Network backend (store the objects remotely, directly)</li>
+ <li>...Oh my god, so many cool ideas!</li>
+ </ul>

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