Fixed Windows DLL builds of test targets

This is a heavily modified version of
https://github.com/abseil/abseil-cpp/pull/1445,
which adds some missing test libraries to the test DLL.

Unlike #1445, this change moves several global variables out of
headers that did not need to be in headers.

For instance, cord_btree_exhaustive_validation was a global
defined/declared in cord_internal, but only used in cord_rep_btree
and its test.

cordz_handle defined a queue in its header even though it wasn't needed,
which also led to ODR problems.

The Spinlock used in CordzHandle is replaced with a Mutex. This was
originally a Mutex, but Chromium asked us to change it to a Spinlock
to avoid a static initializer. After this change, the static
initializer is no longer an issue.

#1407

PiperOrigin-RevId: 531516991
Change-Id: I0e431a193698b20ba03fac6e414c26f153f330a7

7 files changed, 71 insertions, 68 deletions

diff --git a/absl/strings/internal/cord_internal.cc b/absl/strings/internal/cord_internal.cc
index b6b06cfa..b7874385 100644
--- a/absl/strings/internal/cord_internal.cc
+++ b/absl/strings/internal/cord_internal.cc
@@ -33,7 +33,6 @@ ABSL_CONST_INIT std::atomic<bool> cord_ring_buffer_enabled(
     kCordEnableRingBufferDefault);
 ABSL_CONST_INIT std::atomic<bool> shallow_subcords_enabled(
     kCordShallowSubcordsDefault);
-ABSL_CONST_INIT std::atomic<bool> cord_btree_exhaustive_validation(false);
 
 void LogFatalNodeType(CordRep* rep) {
   ABSL_INTERNAL_LOG(FATAL, absl::StrCat("Unexpected node type: ",
diff --git a/absl/strings/internal/cord_internal.h b/absl/strings/internal/cord_internal.h
index e6f0d544..8d9836ba 100644
--- a/absl/strings/internal/cord_internal.h
+++ b/absl/strings/internal/cord_internal.h
@@ -69,12 +69,6 @@ enum CordFeatureDefaults {
 extern std::atomic<bool> cord_ring_buffer_enabled;
 extern std::atomic<bool> shallow_subcords_enabled;
 
-// `cord_btree_exhaustive_validation` can be set to force exhaustive validation
-// in debug assertions, and code that calls `IsValid()` explicitly. By default,
-// assertions should be relatively cheap and AssertValid() can easily lead to
-// O(n^2) complexity as recursive / full tree validation is O(n).
-extern std::atomic<bool> cord_btree_exhaustive_validation;
-
 inline void enable_cord_ring_buffer(bool enable) {
   cord_ring_buffer_enabled.store(enable, std::memory_order_relaxed);
 }
diff --git a/absl/strings/internal/cord_rep_btree.cc b/absl/strings/internal/cord_rep_btree.cc
index a86fdc0b..05bd0e20 100644
--- a/absl/strings/internal/cord_rep_btree.cc
+++ b/absl/strings/internal/cord_rep_btree.cc
@@ -14,6 +14,7 @@
 
 #include "absl/strings/internal/cord_rep_btree.h"
 
+#include <atomic>
 #include <cassert>
 #include <cstdint>
 #include <iostream>
@@ -49,9 +50,7 @@ using CopyResult = CordRepBtree::CopyResult;
 constexpr auto kFront = CordRepBtree::kFront;
 constexpr auto kBack = CordRepBtree::kBack;
 
-inline bool exhaustive_validation() {
-  return cord_btree_exhaustive_validation.load(std::memory_order_relaxed);
-}
+ABSL_CONST_INIT std::atomic<bool> cord_btree_exhaustive_validation(false);
 
 // Implementation of the various 'Dump' functions.
 // Prints the entire tree structure or 'rep'. External callers should
@@ -362,6 +361,15 @@ struct StackOperations {
 
 }  // namespace
 
+void SetCordBtreeExhaustiveValidation(bool do_exaustive_validation) {
+  cord_btree_exhaustive_validation.store(do_exaustive_validation,
+                                         std::memory_order_relaxed);
+}
+
+bool IsCordBtreeExhaustiveValidationEnabled() {
+  return cord_btree_exhaustive_validation.load(std::memory_order_relaxed);
+}
+
 void CordRepBtree::Dump(const CordRep* rep, absl::string_view label,
                         bool include_contents, std::ostream& stream) {
   stream << "===================================\n";
@@ -450,7 +458,8 @@ bool CordRepBtree::IsValid(const CordRepBtree* tree, bool shallow) {
     child_length += edge->length;
   }
   NODE_CHECK_EQ(child_length, tree->length);
-  if ((!shallow || exhaustive_validation()) && tree->height() > 0) {
+  if ((!shallow || IsCordBtreeExhaustiveValidationEnabled()) &&
+      tree->height() > 0) {
     for (CordRep* edge : tree->Edges()) {
       if (!IsValid(edge->btree(), shallow)) return false;
     }
diff --git a/absl/strings/internal/cord_rep_btree.h b/absl/strings/internal/cord_rep_btree.h
index 4209e512..be94b62e 100644
--- a/absl/strings/internal/cord_rep_btree.h
+++ b/absl/strings/internal/cord_rep_btree.h
@@ -32,6 +32,14 @@ namespace absl {
 ABSL_NAMESPACE_BEGIN
 namespace cord_internal {
 
+// `SetCordBtreeExhaustiveValidation()` can be set to force exhaustive
+// validation in debug assertions, and code that calls `IsValid()`
+// explicitly. By default, assertions should be relatively cheap and
+// AssertValid() can easily lead to O(n^2) complexity as recursive / full tree
+// validation is O(n).
+void SetCordBtreeExhaustiveValidation(bool do_exaustive_validation);
+bool IsCordBtreeExhaustiveValidationEnabled();
+
 class CordRepBtreeNavigator;
 
 // CordRepBtree is as the name implies a btree implementation of a Cordrep tree.
diff --git a/absl/strings/internal/cord_rep_btree_test.cc b/absl/strings/internal/cord_rep_btree_test.cc
index 82aeca37..840acf9f 100644
--- a/absl/strings/internal/cord_rep_btree_test.cc
+++ b/absl/strings/internal/cord_rep_btree_test.cc
@@ -1355,9 +1355,9 @@ TEST(CordRepBtreeTest, AssertValid) {
 
 TEST(CordRepBtreeTest, CheckAssertValidShallowVsDeep) {
   // Restore exhaustive validation on any exit.
-  const bool exhaustive_validation = cord_btree_exhaustive_validation.load();
+  const bool exhaustive_validation = IsCordBtreeExhaustiveValidationEnabled();
   auto cleanup = absl::MakeCleanup([exhaustive_validation] {
-    cord_btree_exhaustive_validation.store(exhaustive_validation);
+    SetCordBtreeExhaustiveValidation(exhaustive_validation);
   });
 
   // Create a tree of at least 2 levels, and mess with the original flat, which
@@ -1372,7 +1372,7 @@ TEST(CordRepBtreeTest, CheckAssertValidShallowVsDeep) {
   }
   flat->length = 100;
 
-  cord_btree_exhaustive_validation.store(false);
+  SetCordBtreeExhaustiveValidation(false);
   EXPECT_FALSE(CordRepBtree::IsValid(tree));
   EXPECT_TRUE(CordRepBtree::IsValid(tree, true));
   EXPECT_FALSE(CordRepBtree::IsValid(tree, false));
@@ -1382,7 +1382,7 @@ TEST(CordRepBtreeTest, CheckAssertValidShallowVsDeep) {
   EXPECT_DEBUG_DEATH(CordRepBtree::AssertValid(tree, false), ".*");
 #endif
 
-  cord_btree_exhaustive_validation.store(true);
+  SetCordBtreeExhaustiveValidation(true);
   EXPECT_FALSE(CordRepBtree::IsValid(tree));
   EXPECT_FALSE(CordRepBtree::IsValid(tree, true));
   EXPECT_FALSE(CordRepBtree::IsValid(tree, false));
diff --git a/absl/strings/internal/cordz_handle.cc b/absl/strings/internal/cordz_handle.cc
index a73fefed..a7061dbe 100644
--- a/absl/strings/internal/cordz_handle.cc
+++ b/absl/strings/internal/cordz_handle.cc
@@ -16,34 +16,60 @@
 #include <atomic>
 
 #include "absl/base/internal/raw_logging.h"  // For ABSL_RAW_CHECK
-#include "absl/base/internal/spinlock.h"
+#include "absl/synchronization/mutex.h"
 
 namespace absl {
 ABSL_NAMESPACE_BEGIN
 namespace cord_internal {
 
-using ::absl::base_internal::SpinLockHolder;
+namespace {
 
-ABSL_CONST_INIT CordzHandle::Queue CordzHandle::global_queue_(absl::kConstInit);
+struct Queue {
+  Queue() = default;
+
+  absl::Mutex mutex;
+  std::atomic<CordzHandle*> dq_tail ABSL_GUARDED_BY(mutex){nullptr};
+
+  // Returns true if this delete queue is empty. This method does not acquire
+  // the lock, but does a 'load acquire' observation on the delete queue tail.
+  // It is used inside Delete() to check for the presence of a delete queue
+  // without holding the lock. The assumption is that the caller is in the
+  // state of 'being deleted', and can not be newly discovered by a concurrent
+  // 'being constructed' snapshot instance. Practically, this means that any
+  // such discovery (`find`, 'first' or 'next', etc) must have proper 'happens
+  // before / after' semantics and atomic fences.
+  bool IsEmpty() const ABSL_NO_THREAD_SAFETY_ANALYSIS {
+    return dq_tail.load(std::memory_order_acquire) == nullptr;
+  }
+};
+
+static Queue* GlobalQueue() {
+  static Queue* global_queue = new Queue;
+  return global_queue;
+}
+
+}  // namespace
 
 CordzHandle::CordzHandle(bool is_snapshot) : is_snapshot_(is_snapshot) {
+  Queue* global_queue = GlobalQueue();
   if (is_snapshot) {
-    SpinLockHolder lock(&queue_->mutex);
-    CordzHandle* dq_tail = queue_->dq_tail.load(std::memory_order_acquire);
+    MutexLock lock(&global_queue->mutex);
+    CordzHandle* dq_tail =
+        global_queue->dq_tail.load(std::memory_order_acquire);
     if (dq_tail != nullptr) {
       dq_prev_ = dq_tail;
       dq_tail->dq_next_ = this;
     }
-    queue_->dq_tail.store(this, std::memory_order_release);
+    global_queue->dq_tail.store(this, std::memory_order_release);
   }
 }
 
 CordzHandle::~CordzHandle() {
-  ODRCheck();
+  Queue* global_queue = GlobalQueue();
   if (is_snapshot_) {
     std::vector<CordzHandle*> to_delete;
     {
-      SpinLockHolder lock(&queue_->mutex);
+      MutexLock lock(&global_queue->mutex);
       CordzHandle* next = dq_next_;
       if (dq_prev_ == nullptr) {
         // We were head of the queue, delete every CordzHandle until we reach
@@ -59,7 +85,7 @@ CordzHandle::~CordzHandle() {
       if (next) {
         next->dq_prev_ = dq_prev_;
       } else {
-        queue_->dq_tail.store(dq_prev_, std::memory_order_release);
+        global_queue->dq_tail.store(dq_prev_, std::memory_order_release);
       }
     }
     for (CordzHandle* handle : to_delete) {
@@ -69,16 +95,15 @@ CordzHandle::~CordzHandle() {
 }
 
 bool CordzHandle::SafeToDelete() const {
-  return is_snapshot_ || queue_->IsEmpty();
+  return is_snapshot_ || GlobalQueue()->IsEmpty();
 }
 
 void CordzHandle::Delete(CordzHandle* handle) {
   assert(handle);
   if (handle) {
-    handle->ODRCheck();
-    Queue* const queue = handle->queue_;
+    Queue* const queue = GlobalQueue();
     if (!handle->SafeToDelete()) {
-      SpinLockHolder lock(&queue->mutex);
+      MutexLock lock(&queue->mutex);
       CordzHandle* dq_tail = queue->dq_tail.load(std::memory_order_acquire);
       if (dq_tail != nullptr) {
         handle->dq_prev_ = dq_tail;
@@ -93,8 +118,9 @@ void CordzHandle::Delete(CordzHandle* handle) {
 
 std::vector<const CordzHandle*> CordzHandle::DiagnosticsGetDeleteQueue() {
   std::vector<const CordzHandle*> handles;
-  SpinLockHolder lock(&global_queue_.mutex);
-  CordzHandle* dq_tail = global_queue_.dq_tail.load(std::memory_order_acquire);
+  Queue* global_queue = GlobalQueue();
+  MutexLock lock(&global_queue->mutex);
+  CordzHandle* dq_tail = global_queue->dq_tail.load(std::memory_order_acquire);
   for (const CordzHandle* p = dq_tail; p; p = p->dq_prev_) {
     handles.push_back(p);
   }
@@ -103,13 +129,13 @@ std::vector<const CordzHandle*> CordzHandle::DiagnosticsGetDeleteQueue() {
 
 bool CordzHandle::DiagnosticsHandleIsSafeToInspect(
     const CordzHandle* handle) const {
-  ODRCheck();
   if (!is_snapshot_) return false;
   if (handle == nullptr) return true;
   if (handle->is_snapshot_) return false;
   bool snapshot_found = false;
-  SpinLockHolder lock(&queue_->mutex);
-  for (const CordzHandle* p = queue_->dq_tail; p; p = p->dq_prev_) {
+  Queue* global_queue = GlobalQueue();
+  MutexLock lock(&global_queue->mutex);
+  for (const CordzHandle* p = global_queue->dq_tail; p; p = p->dq_prev_) {
     if (p == handle) return !snapshot_found;
     if (p == this) snapshot_found = true;
   }
@@ -119,13 +145,13 @@ bool CordzHandle::DiagnosticsHandleIsSafeToInspect(
 
 std::vector<const CordzHandle*>
 CordzHandle::DiagnosticsGetSafeToInspectDeletedHandles() {
-  ODRCheck();
   std::vector<const CordzHandle*> handles;
   if (!is_snapshot()) {
     return handles;
   }
 
-  SpinLockHolder lock(&queue_->mutex);
+  Queue* global_queue = GlobalQueue();
+  MutexLock lock(&global_queue->mutex);
   for (const CordzHandle* p = dq_next_; p != nullptr; p = p->dq_next_) {
     if (!p->is_snapshot()) {
       handles.push_back(p);
diff --git a/absl/strings/internal/cordz_handle.h b/absl/strings/internal/cordz_handle.h
index 3c800b43..9afe9a21 100644
--- a/absl/strings/internal/cordz_handle.h
+++ b/absl/strings/internal/cordz_handle.h
@@ -20,8 +20,6 @@
 
 #include "absl/base/config.h"
 #include "absl/base/internal/raw_logging.h"
-#include "absl/base/internal/spinlock.h"
-#include "absl/synchronization/mutex.h"
 
 namespace absl {
 ABSL_NAMESPACE_BEGIN
@@ -79,37 +77,6 @@ class CordzHandle {
   virtual ~CordzHandle();
 
  private:
-  // Global queue data. CordzHandle stores a pointer to the global queue
-  // instance to harden against ODR violations.
-  struct Queue {
-    constexpr explicit Queue(absl::ConstInitType)
-        : mutex(absl::kConstInit,
-                absl::base_internal::SCHEDULE_COOPERATIVE_AND_KERNEL) {}
-
-    absl::base_internal::SpinLock mutex;
-    std::atomic<CordzHandle*> dq_tail ABSL_GUARDED_BY(mutex){nullptr};
-
-    // Returns true if this delete queue is empty. This method does not acquire
-    // the lock, but does a 'load acquire' observation on the delete queue tail.
-    // It is used inside Delete() to check for the presence of a delete queue
-    // without holding the lock. The assumption is that the caller is in the
-    // state of 'being deleted', and can not be newly discovered by a concurrent
-    // 'being constructed' snapshot instance. Practically, this means that any
-    // such discovery (`find`, 'first' or 'next', etc) must have proper 'happens
-    // before / after' semantics and atomic fences.
-    bool IsEmpty() const ABSL_NO_THREAD_SAFETY_ANALYSIS {
-      return dq_tail.load(std::memory_order_acquire) == nullptr;
-    }
-  };
-
-  void ODRCheck() const {
-#ifndef NDEBUG
-    ABSL_RAW_CHECK(queue_ == &global_queue_, "ODR violation in Cord");
-#endif
-  }
-
-  ABSL_CONST_INIT static Queue global_queue_;
-  Queue* const queue_ = &global_queue_;
   const bool is_snapshot_;
 
   // dq_prev_ and dq_next_ require the global queue mutex to be held.