Vladimir Ozerov created IGNITE-1615:
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Summary: .Net: Perform AtomicLong.get() without JNI if possible.
Key: IGNITE-1615
URL: https://issues.apache.org/jira/browse/IGNITE-1615
Project: Ignite
Issue Type: Task
Components: interop
Affects Versions: ignite-1.4
Reporter: Vladimir Ozerov
Fix For: ignite-1.5
Variables with atomic/interlocked semantics are frequently used in mostly-read
scenarios. E.g. in spin-loops, non-blocking alogrithms, as regular volatiles,
etc..
With current implementation we perform JNI call on every read which is too
expensive, especially with poor Java performance when performing (native ->
JVM) transition.
We can optimize it with the following non-blocking algorithm:
1) Add atomic "stamp" field.
2) Add atomic "cached" field.
3) On any update:
- Do the update;
- Atomically increment the stamp;
4) On any read:
- Read stamp (oldStamp);
- Read cached value;
- Read stamp again (newStamp);
- if (oldStamp == newStamp == cache.stamp()), return cached value.
- Otherwise perform real read through JNI and update cached value with a pair
of (readValue + oldStamp);
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