Optimization: faster target id lookups

From: Vladimir Prus (ghost_at_[hidden])
Date: 2004-12-22 02:42:53

Resolving target-ids (the things you specify in source list) was pretty slow.

Details. There were two issues. First, when <library>foo is specified as 
global requirements, each target gets that property and lookups "foo". We now 
cache the lookup results for each project. Second, when looking up "bar.cpp", 
we first tries to see of "bar.cpp" project exists and then interpreted this 
as file. We now quickly check if if it's a file (using new jam builtin) and 
only then try expensive project lookup.

Compatibility: bjam update and REBUILD is required. 

Performance:
Femtown (reference Boost.Build)
Real: min 23:830, max 30:420, avg 26:66
User: min 22:440, max 23:160, avg 22:713

Femtown (CVS Boost.Build)
Real: min 20:500, max 21:720, avg 21:170
User: min 19:420, max 20:260, avg 19:780

TBLib (reference Boost.Build)
Real: min 11:390, max 13:120, avg 12:240
User: min 11:130, max 12:60, avg 11:580

TBLib (CVS Boost.Build)
Real: min 11:120, max 11:370, avg 11:283
User: min 10:710, max 11:30, avg 10:890

- Volodya