Add caching of results in FunctionFactory::getFunctionNames

[Russell Taylor]

This method is quite expensive as it creates an instance of every registered fitting function every time it's called. It's been found to be called from algorithm init methods where those algorithms are called as child algorithms within a loop in another algorithm.

The cache could be that will have a map<string, vector<string>> where the keys will be type_info.name strings and values are names of functions.

[Russell Taylor]

Re #8634. Add caching of names in FunctionFactory::getFunctionNames.

This method was fairly expensive because it had to create an instance of every registered function every time to find out if it's the requested type. This method is called to create validators in various algorithm init methods, which can be called a lot it - for example - the algorithm is used as a sub-algorithm in a loop within another algorithm.

It's now cached in a map that's a member of FunctionFactoryImpl. The caching had to be made thread-safe with a mutex. On the plus side this allows the resulting vector to be returned by reference-to-const.

Changeset: 4c089bf0fa8e5995b6d590485d5c29488791d35e

[Russell Taylor]

Re #8634. Add some kind of testing for getFunctionNames.

Changeset: 08194357a74b28c0ed12c424b7d649f47bbdd87d

[Russell Taylor]

Re #8634. Take advantage of reference return type.

Changeset: b74c6ea87f28e06e6015765a4d69461c2fd30a63

[Russell Taylor]

Re #8634. Clear cache if functions are added or removed after startup.

Can be done from python, and of course it invalidates the cache.

Changeset: 22085b00607f2b715e5e0c132d9112bc3764dbf0

[Russell Taylor]

Re #8634. Make sure the FrameworkManager is started in tests.

...before the first time getFunctionNames is called. Otherwise the cache will be populated before the functions have been registered.

Changeset: 24d035fb488aa6f2ddfdb41f562eed55ebefd4ef

[Russell Taylor]

Testing should be largely by inspection, as the external behaviour should be unchanged (which is verified by seeing that all tests are passing).

Not the speed improvement in ​https://builds.sns.gov/view/Tests/job/mantid_performance_tests_develop/Develop_branch_performance_tests/AlgorithmsTest.GetDetOffsetsMultiPeaksTestPerformance.test_performance.htm, which is what prompted this work.

[Peter Peterson]

Merge remote branch 'origin/feature/8634_functionfactory_getfunctionnames_caching'

Full changeset: ​8aadb09a47b4f6a657c3bac60d5e6ed05310fb81

[Stuart Campbell]

This ticket has been transferred to github issue ​9478