## Configuration
-When you first run CMake on Junction, Turf will detect the capabilities of your compiler and write the results to a file in the build tree named `include/turf_config.h`. Similarly, Junction will write `include/junction_config.h` to the build tree. You can modify the contents of those files by setting variables when CMake runs. This can be done by passing additional options to `cmake`, or by using an interactive GUI such as `cmake-gui` or `ccmake`.
+When you first run CMake on Junction, Turf will detect the capabilities of your compiler and write the results to a file in the build tree named `turf/include/turf_config.h`. Similarly, Junction will write `include/junction_config.h` to the build tree. You can modify the contents of those files by setting variables when CMake runs. This can be done by passing additional options to `cmake`, or by using an interactive GUI such as `cmake-gui` or `ccmake`.
For example, to configure Turf to use the C++11 standard library, you can set the `TURF_PREFER_CPP11` variable on the command line:
## Rules and Behavior
-Currently, Junction maps only work with keys and values that are pointers or pointer-sized integers. The hash function must be invertible, so that every key has a unique hash. Otherwise, a Junction map is a lot like a big array of `std::atomic<>` variables, where the key is an index into the array. More precisely:
+Currently, Junction maps only work with keys and values that are pointers or pointer-sized integers. The hash function must be invertible, so that every key has a unique hash. Out of all possible keys, a _null_ key must be reserved, and out of all possible values, _null_ and _redirect_ values must be reserved. The defaults are 0 and 1. You can override those defaults by passing custom `KeyTraits` and `ValueTraits` parameters to the template.
+
+Every thread that manipulates a Junction map must periodically call `junction::DefaultQSBR.update`, as mentioned [in the blog post](http://preshing.com/20160201/new-concurrent-hash-maps-for-cpp/). If not, the application will leak memory.
+
+Otherwise, a Junction map is a lot like a big array of `std::atomic<>` variables, where the key is an index into the array. More precisely:
* All of a Junction map's member functions, together with its `Mutator` member functions, are atomic with respect to each other, so you can safely call them from any thread without mutual exclusion.
* If an `assign` [happens before](http://preshing.com/20130702/the-happens-before-relation/) a `get` with the same key, the `get` will return the value it inserted, except if another operation changes the value in between. Any [synchronizing operation](http://preshing.com/20130823/the-synchronizes-with-relation/) will establish this relationship.
projects / junction.git / blobdiff