DLI Implementation and Reference Guide - Datalogics

2.14 DLI Implementation and Reference Guide
example, the following sequence will cause errors when attempting to initialize
Thread 2:
Concepts and dlpdfinit() Facilities: Guide to the DL Pager Composition System
[Thread 1 processing]
dlpdfterm()
dlpdfinit()
[Thread 2 processing]
dlpdfterm()
The problem above is that when Thread 1 terminates, no other processes are seen, and
so shutdown cleanup work begins, leading to errors when the initialization of Thread
2 comes along.
This sequence is recommended instead:
dlpdfinit()
dlpdfinit()
[thread 1 processing]
[thread 2 processing]
dlpdfterm()
dlpdfterm()
Thread-Safe Issues
Releases of the Adobe PDF Library prior to v6.1 are not thread-safe, and so by
extension neither is DLI. Adobe PDF Library v6.1 and its accompanying DLI is the
first thread-safe release in distribution. Notes on use of prior versions within multithreaded
applications are given below. It is possible to use pre-v6.1, non-thread-safe
Library applications in a threaded environment under the proper configuration in
certain circumstances (although you should plan to upgrade your application to a
thread-safe Adobe PDF Library v6.1.x version at your next opportunity).
The general idea is that your application will queue the threads' interaction with the
Library functions so that they are executed one at a time. This is not too difficult to do
if your pre-v6.1.x application uses a mutex (Mutual Exclusion) algorithm to ensure
that only one thread has access to the Library at any given point in time. Testing has
shown that execution time does not appear negatively impacted if the Library
segments are efficiently grouped, so that any given thread's Library activity is over
and done with before the next process calls. When properly implemented, there