Rewrite/simplify tracing.

The implementation so far was prematurely optimized. It had all threads record directly into a shared vector indexed by block_ids. The idea was (1) to avoid the overhead of locking or other synchronization primitives when tracing a multi-thread execution, and (2) to avoid overhead of growing heap buffers. The new implementation is much more straightforward, as is most evident from the fact that it doesn't use relaxed_atomic_store anymore (yet still runs free of TSan errors), and that we were able to remove the ProcessedTrace class.

The above-mentioned issues (1) and (2) that drove the earlier design are now addressed as follows in the new design: (1) Each thread now records to its own specific vector of trace entries; these thread-specific vectors are only coalesced into a global vector when dumping a trace. This removed the need for any locking or atomic operations. (2) We are less careful than before about avoiding heap allocations. We just reserve upfront a rather large buffer size, large enough to avoid most subsequent heap reallocations and small enough to still not matter in practical tracing situations.

The proximate motivation for this change is that the existing design, requiring indexing of trace entries by block_id, is now inconvenient as we need to experiment with TrMul implementation changes where packing is not necessarily directly associated with a block_ids anymore.

PiperOrigin-RevId: 259996147

1 files changed, 0 insertions, 1 deletions

diff --git a/BUILD b/BUILD
index 5fd7936..33e8f14 100644
--- a/BUILD
+++ b/BUILD
@@ -195,7 +195,6 @@ cc_library(
     deps = [
         ":block_map",
         ":check_macros",
-        ":common",
         ":side_pair",
         ":time",
     ],