Squid internals

The Storage Manager (src/store*.c)
Passing data back to store clients - InvokeHandlers()
InvokeHandlers() is called to check the store clients waiting for data on a StoreEntry
It checks to see whether the data is avaliable in memory and if so
calls the callback supplied in storeClientCopy()
InvokeHandlers() does not handle STORE_DISK_CLIENTs