[ccache] ccache miss increasing on making same build

[Joel Rosdahl]

Hi Vijay,

For me, ccache is not working properly on compiling the already compiled
> build again. I can see "ccache miss" count increasing instead of "ccache
> hit" count.


To be able to understand why, it would help to get a ccache log that
contains:

1. A compilation of a source file X, leading to a cache miss (and storage
of the result in the cache).
2. A repeated compilation of the same source file X, leading to a cache
miss (where you expected a cache hit of the previous result).

The log file you attached only contains cache misses for two *different*
source files.

However, one thing I noticed in your log is that the manifest file already
exists. This likely means that one of the include files has changed content
between the two compilations. To find out which one, get the path of the
manifest from the ccache log file (search for "Looking for object file hash
in .../<hash>-<length>.manifest") and dump the manifest with this script:

https://git.samba.org/?p=ccache.git;a=blob_plain;f=dump-manifest;hb=326bcbfda8709db5ad6c21ff6b0e62f0441d27d9

(Or, upgrade to ccache 3.2 and run "ccache --dump-manifest
path/to/the.manifest".)

You can send the dumped manifest to me (or to the list if it's not too
large) and I'll have a look.

-- Joel