Initial code for trace api.

1 files changed, 53 insertions, 0 deletions

diff --git a/src/usr/trace/TraceBuffer.C b/src/usr/trace/TraceBuffer.C
new file mode 100644
index 000000000..c10afcfa3
--- /dev/null
+++ b/src/usr/trace/TraceBuffer.C
@@ -0,0 +1,53 @@
+#include <limits.h>
+#include "TraceBuffer.H"
+
+TracePage* TracePage::setNext(TracePage* new_next)
+{
+    return __sync_val_compare_and_swap(&this->next, NULL, new_next);
+}
+
+traceEntry* TracePage::claimEntry(size_t size)
+{
+    size_t position = __sync_fetch_and_add(&this->size, size);
+    if (position > (PAGE_SIZE - sizeof(TracePage)))
+    {
+        return NULL;
+    }
+    else
+    {
+        return (traceEntry*)&((uint8_t*)this)[sizeof(TracePage) + position];
+    }
+}
+
+traceEntry* TraceBuffer::claimEntry(size_t size)
+{
+    traceEntry* result = NULL;
+    TracePage* page = last;
+
+    while (result == NULL)
+    {
+        result = page->claimEntry(size);
+
+        if (NULL == result)
+        {
+            if (NULL != page->getNext())
+            {
+                __sync_bool_compare_and_swap(&this->last, 
+                                             page, page->getNext());
+                page = page->getNext();
+            }
+            else
+            {
+                TracePage* new_page = new (malloc(PAGE_SIZE)) TracePage();
+                TracePage* prev = page;
+
+                while(prev != NULL)
+                {
+                    prev = prev->setNext(new_page);
+                }
+            }
+        }
+    }
+
+    return result;
+}