The handshakes support for virtual threads is needed to simplify the JVMTI implementation for virtual threads. There is a significant duplication in the JVMTI code to differentiate code intended to support platform, virtual threads or both. The handshakes are unified, so it is enough to define just one handshake for both platform and virtual thread. At the low level, the JVMTI code supporting platform and virtual threads still can be different. This implementation is based on the `JvmtiVTMSTransitionDisabler` class.
The interface includes, at least, two new classes: - `JvmtiHandshake` and `JvmtiUnifiedHandshakeClosure` The `JvmtiUnifiedHandshakeClosure` defines two different callback functions: `do_thread()` and `do_vthread()`. The first JVMTI functions are picked first to be converted to use the `JvmtiHandshake`: - `GetStackTrace`, `GetFrameCount`, `GetFrameLocation`, `NotifyFramePop` Testing: - the mach5 tiers 1-6 are all passed ------------- Commit messages: - 8319244: implement JVMTI handshakes support for virtual threads Changes: https://git.openjdk.org/jdk/pull/16460/files Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=16460&range=00 Issue: https://bugs.openjdk.org/browse/JDK-8319244 Stats: 532 lines in 5 files changed: 176 ins; 329 del; 27 mod Patch: https://git.openjdk.org/jdk/pull/16460.diff Fetch: git fetch https://git.openjdk.org/jdk.git pull/16460/head:pull/16460 PR: https://git.openjdk.org/jdk/pull/16460
