commit 6276a3236f72ab7abd30cd9bbbc486edb0998f82
author pigweed-integration-roller <pigweed-integration-roller@pigweed.google.com.iam.gserviceaccount.com> Tue Jul 13 17:39:02 2021 +0000
committer CQ Bot Account <pigweed-scoped@luci-project-accounts.iam.gserviceaccount.com> Tue Jul 13 17:45:36 2021 +0000
tree 82b2f277b98bc50a3608a6cd9376b81d589fdc38
parent 672f889ef8fecf78fd2d609294940172db434cb4

[roll third_party/pigweed] pw_ring_buffer: Add ring buffer iterator

To support walking through the ring buffers in crash contexts, it's
useful to have a mechanism that allows processing entries in the ring
buffer without requiring buffer copies (in favor of raw access). This
adds a new unsafe iteration class that can be used while the caller has
a guarantee that the underlying buffer is not being mutated.

The multisink is also updated to support this unsafe iteration by adding
an oldest entry reader that is used as a reference point for the
iterator class. This will additionally support late-drain attach flows
where a drain may want to match the oldest entry available in the
buffer, as opposed to the current logic that always starts it at the
write index.

Original-Bug: b/190547664
Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/50262

third_party/pigweed Rolled-Commits: 2d4fa78d91e9cb9..16541e7699118f3
Roller-URL: https://ci.chromium.org/b/8841801673210791616
Cq-Cl-Tag: roller-builder:pigweed-experimental-roller
Cq-Cl-Tag: roller-bid:8841801673210791616
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: I6aeea8aee0158646fbd7ee9d1b571018495b5804
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/experimental/+/52980
Reviewed-by: Pigweed Integration Roller <pigweed-integration-roller@pigweed.google.com.iam.gserviceaccount.com>
Commit-Queue: Pigweed Integration Roller <pigweed-integration-roller@pigweed.google.com.iam.gserviceaccount.com>