Export of internal Abseil changes

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341670bce317dd6af8d3c066970230591a47e80c by Martijn Vels <mvels@google.com>:

Change GetStack() and GetParentStack() to return absl::Span

PiperOrigin-RevId: 368765721

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6aaab9536d6957303c7aba100c3afaa6fb0ea2c8 by Martijn Vels <mvels@google.com>:

Remove locking from parent stack.

This change removes the need to lock all access to `parent_stack' by making the 'copy constructor' logic specify the 'copied from' CordzInfo (where available) to the TrackCord function, after which parent_stack is immutable.

PiperOrigin-RevId: 368760630

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b19e2059cada35a8ede994833018edac94de6ddc by Martijn Vels <mvels@google.com>:

Add cordz instrumentation to Cord

PiperOrigin-RevId: 368746225

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67b8bbf980f0f4e1db79aa32968e9a715a09b51a by Martijn Vels <mvels@google.com>:

Create ABSL_INTERNAL_CORDZ_ENABLED define controlling when Cordz code is enabled

There are specific builds and condtions under which we don't support cordz sampling, which is per this change represented by ABSL_INTERNAL_CORDZ_ENABLED being defined.

PiperOrigin-RevId: 368731603

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8cbfe0e3169637a620f4b66ad2bc2ce340879cb0 by Martijn Vels <mvels@google.com>:

Add a `rep` property to CordzInfo to be managed by Cord logic.

This change adds a `rep` property to CordzInfo, which is intended to be used by collection logic.

Mini design:
Cord invokes TrackCord() providing the active 'root' cordrep of the newly sampled Cord, returning a CordzInfo with a weak (uncounted) reference to this root. Cord invokes `SetCordRep()` each time the root cordrep of the sampled Cord is updated while holding `mutex()`. Cord must also obtain `mutex()` _before_ removing a reference on the old root. i.e.: Cord must guarantee that the (weak) reference held in CordzInfo is at all times valid.

CordzInfo collection code can then safely obtain a (reference counted) rep pointer by adding a reference to `rep_` while holding `mutex()`. This requires only a very brief critical section inside CordzInfo logic, minimizing contention with concurrent Cord updates.

Cord code should typically obtain and hold `mutex()` for the entirety of each mutating Cord operation on a sampled cord. As Cord is thread compatible, it never competes on the lock with any other thread. The only possible concurrent access is from Cordz collection code, which should be a relatively rare event.

PiperOrigin-RevId: 368673758

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1255120dce2bdd6b4205a34a0e555e0b74b6152f by Martijn Vels <mvels@google.com>:

Remove 'depth' from active recorded metrics.

Going forward we do not 'live' record depth (and size), but will observe these at collection time only.

PiperOrigin-RevId: 368636572

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83e5146e35f221736b49e9f0a8805f8c159a51db by Martijn Vels <mvels@google.com>:

Make cordz targets visible in OSS

PiperOrigin-RevId: 368615010

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dcb16a4f1239151f0a8c70a8cfeb29dabbd113b8 by Martijn Vels <mvels@google.com>:

Internal cleanup

PiperOrigin-RevId: 368514666
GitOrigin-RevId: 341670bce317dd6af8d3c066970230591a47e80c
Change-Id: I94cecfbbd441eb386f99fc5186c468a7a5538862

1 files changed, 13 insertions, 4 deletions

diff --git a/CMake/AbseilDll.cmake b/CMake/AbseilDll.cmake
index 4527ca14..2f2fa13d 100644
--- a/CMake/AbseilDll.cmake
+++ b/CMake/AbseilDll.cmake
@@ -197,17 +197,26 @@ set(ABSL_INTERNAL_DLL_FILES
   "strings/cord.h"
   "strings/escaping.cc"
   "strings/escaping.h"
+  "strings/internal/charconv_bigint.cc"
+  "strings/internal/charconv_bigint.h"
+  "strings/internal/charconv_parse.cc"
+  "strings/internal/charconv_parse.h"
   "strings/internal/cord_internal.cc"
   "strings/internal/cord_internal.h"
   "strings/internal/cord_rep_flat.h"
   "strings/internal/cord_rep_ring.cc"
   "strings/internal/cord_rep_ring.h"
   "strings/internal/cord_rep_ring_reader.h"
+  "strings/internal/cordz_functions.cc"
+  "strings/internal/cordz_functions.h"
+  "strings/internal/cordz_handle.cc"
+  "strings/internal/cordz_handle.h"
+  "strings/internal/cordz_info.cc"
+  "strings/internal/cordz_info.h"
+  "strings/internal/cordz_sample_token.cc"
+  "strings/internal/cordz_sample_token.h"
+  "strings/internal/cordz_statistics.h"
   "strings/internal/cordz_update_tracker.h"
-  "strings/internal/charconv_bigint.cc"
-  "strings/internal/charconv_bigint.h"
-  "strings/internal/charconv_parse.cc"
-  "strings/internal/charconv_parse.h"
   "strings/internal/stl_type_traits.h"
   "strings/internal/string_constant.h"
   "strings/match.cc"