Changeset 3caf5e3 for libcfa

Timestamp:

Mar 23, 2022, 1:23:17 PM (2 years ago)

Author:

Thierry Delisle <tdelisle@…>

Branches:

ADT, ast-experimental, enum, master, pthread-emulation, qualifiedEnum

Children:

202c80b, 94fa946

Parents:

1a567d0

Message:

Re-read cq information after acquire. Hoping this is the cause for the build failure

File:

• libcfa/src/concurrency/io.cfa (modified) (2 diffs)

libcfa/src/concurrency/io.cfa

@@ -99 +99 @@
                 /* paranoid */ verify( ctx );
 
+                const __u32 mask = *ctx->cq.mask;
+
+
+                {
+                        const __u32 head = *ctx->cq.head;
+                        const __u32 tail = *ctx->cq.tail;
+
+                        if(head == tail) return false;
+                }
+
                 // Drain the queue
-                unsigned head = *ctx->cq.head;
-                unsigned tail = *ctx->cq.tail;
-                const __u32 mask = *ctx->cq.mask;
-
-                __u32 count = tail - head;
-                __STATS__( false, io.calls.drain++; io.calls.completed += count; )
-
-                if(count == 0) return false;
-
                 if(!__atomic_try_acquire(&ctx->cq.lock)) {
                         return false;
@@ -114 +115 @@
 
                 unsigned long long ts_prev = ctx->cq.ts;
+
+                // re-read the head and tail in case it already changed.
+                const __u32 head = *ctx->cq.head;
+                const __u32 tail = *ctx->cq.tail;
+                const __u32 count = tail - head;
+                __STATS__( false, io.calls.drain++; io.calls.completed += count; )
 
                 for(i; count) {