RFR: 8286441: Remove mode parameter from jdk.internal.perf.Perf.attach()

[Claes Redestad]

On Tue, 10 May 2022 04:00:29 GMT, Ioi Lam <iklam at openjdk.org> wrote:

> The `mode` parameter for ` jdk.internal.perf.Perf.attach()` has never supported the value `"rw"` since the source code was imported to the openjdk repo more than 15 years ago. In fact HotSpot throws `IllegalArgumentException` when such a mode is specified.
> 
> It's unlikely such a mode will be required for future enhancements. Support for `"rw"` is removed. The "mode" parameter is also removed, since now `"r"` is the only supported mode.
> 
> I also cleaned up related code in the JDK and HotSpot.
> 
> Testing:
> - Passed tiers 1 and 2
> - Tiers 3, 4, 5 are in progress

Nice cleanup!

(Some stylistic suggestions inline, feel free to ignore)

src/hotspot/os/windows/perfMemory_windows.cpp line 1781:

> 1779: // address space.
> 1780: //
> 1781: void PerfMemory::attach(const char* user, int vmid,

One line?

src/hotspot/share/prims/perf.cpp line 84:

> 82: 
> 83:   // attach to the PerfData memory region for the specified VM
> 84:   PerfMemory::attach(user_utf, vmid,

One line?

src/hotspot/share/runtime/perfMemory.hpp line 146:

> 144:     // methods for attaching to and detaching from the PerfData
> 145:     // memory segment of another JVM process on the same system.
> 146:     static void attach(const char* user, int vmid,

One line?

src/jdk.jstatd/share/classes/sun/tools/jstatd/RemoteHostImpl.java line 74:

> 72:         Integer v = lvmid;
> 73:         RemoteVm stub = null;
> 74:         StringBuilder sb = new StringBuilder();

Suggestion:

        String vmidStr = "local://" + lvmid + "@localhost";

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Marked as reviewed by redestad (Reviewer).

PR: https://git.openjdk.java.net/jdk/pull/8622