savemessage_getnewheader was an undocmented, cryptic and overengineered
function. It generates a new unique value that can be used as a mail
header to be inserted. For this it used LOTS of randomness sources: hash
of the mail content, hash of the folder name, hash of the repository
name, the current time, a random() value, and the offlineimap version string.
All we need is something random. So reduce this to hash of content
appended by a random integer. Sufficient and somewhat faster to calculate.
Rename the function to actually describe accurately what it does or
would you have guessed that savemessage_getnewheader() did nothing more
than returning ('X-OfflineIMAP', <randomstring> )? Rename to
generate_randomheader() to make it clearer what this is all about.
Also document the function, describing what it does, and what it returns.
Signed-off-by: Sebastian Spaeth <Sebastian@SSpaeth.de>
Signed-off-by: Nicolas Sebrecht <nicolas.s-dev@laposte.net>
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