CODEWITHSUNDEEP
eclipsepluginscircular-dependency
martin jakubik
martin jakubik

Reputation: 4148

Despite circular dependency error in Eclipse plugin export, I cannot find cycle in dependencies: how to debug this?

when I try to export a plug-in using Eclipse, I get the error message "A cycle was detected when generating the classpath".

This is followed by a list of plug-ins which apparently shows the cycle, in this form:

a.b.c.plugin-u_version,
**a.b.c.plugin-w_version**,
a.b.c.plugin-x_version,
a.b.c.plugin-y_version,
a.b.c.plugin-z_version,
**a.b.c.plugin-w_version**.

Note that according to this list, it appears that plugin-w depends on plugin-z, but plugin-z depends on plugin-w.

When I check the dependencies of these plugins, both by opening the MANIFEST.MF and checking the Dependencies tab, and by looking at the Required-bundle: property in the manifest, I confirm all of these dependencies, up until the very last one.

That is, in the MANIFEST.MF for a.b.c.plugin-z, I do not see any dependency on plugin-w.

Am I reading the error right? If so, how can I debug where the error is coming from?

Upvotes: 0

Views: 2035

Answers (2)

Rick
Rick

Reputation: 11

Another quick and dirty solution is to check the "Allow for binary cycles in target platform" checkbox at the bottom of the Export window.

Upvotes: 1

martin jakubik
martin jakubik

Reputation: 4148

This question is difficult to generalize, and I have not done the tedious full analysis needed to, so I'm answering my own question and hoping it helps others who search for the same error.

The error I get, when exporting a plug-in, is "A cycle was detected when generating the classpath", but I don't see the cycle by examining the dependencies of each plug-in.

The problem comes from the fact that there is a fragment involved. One of the plug-ins in the chain, let's say it's plugin.x, above, is a fragment host for another plug-in that is not listed in the dependency chain, and that that second plug-in has a dependency that introduces the cycle.

Let's call the plug-in that is not listed in the dependency chain, "plugin.x1".

In the MANIFEST.MF file for plugin.x1, I see the attribute "Fragment-Host: a.b.c.plugin-x". This attribute makes plugin-x dependent on plugin-x1.

But another attribute in the MANIFEST.MF file for plugin.x1 reads: "Import-Package: a.b.c.plugin-w".

So the dependency is: w depends on x; x is a fragment host for x1; and x1 depends on w. Thus the cycle.

The clean solution is: redesign my code to avoid circular dependencies by avoiding the fragment host configuration.

The quick and dirty solution, which works for me is: close the project plugin.x1 whenever I want to export my plugin.u.

Upvotes: 1

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