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-rw-r--r--absl/strings/cord.cc30
-rw-r--r--absl/strings/cord_test.cc21
-rw-r--r--absl/strings/internal/cord_internal.cc7
-rw-r--r--absl/strings/internal/cord_internal.h58
4 files changed, 60 insertions, 56 deletions
diff --git a/absl/strings/cord.cc b/absl/strings/cord.cc
index 6547c2da..b65dc58b 100644
--- a/absl/strings/cord.cc
+++ b/absl/strings/cord.cc
@@ -151,23 +151,6 @@ void InitializeCordRepExternal(absl::string_view data, CordRepExternal* rep) {
} // namespace cord_internal
-static CordRep* NewSubstring(CordRep* child, size_t offset, size_t length) {
- // Never create empty substring nodes
- if (length == 0) {
- CordRep::Unref(child);
- return nullptr;
- } else {
- CordRepSubstring* rep = new CordRepSubstring();
- assert(child->IsExternal() || child->IsFlat());
- assert((offset + length) <= child->length);
- rep->length = length;
- rep->tag = cord_internal::SUBSTRING;
- rep->start = offset;
- rep->child = child;
- return VerifyTree(rep);
- }
-}
-
// Creates a CordRep from the provided string. If the string is large enough,
// and not wasteful, we move the string into an external cord rep, preserving
// the already allocated string contents.
@@ -643,7 +626,7 @@ static CordRep* RemovePrefixFrom(CordRep* node, size_t n) {
start += node->substring()->start;
node = node->substring()->child;
}
- node = NewSubstring(CordRep::Ref(node), start, len);
+ node = CordRepSubstring::Create(CordRep::Ref(node), start, len);
}
while (!rhs_stack.empty()) {
node = Concat(node, CordRep::Ref(rhs_stack.back()));
@@ -678,7 +661,7 @@ static CordRep* RemoveSuffixFrom(CordRep* node, size_t n) {
start = node->substring()->start;
node = node->substring()->child;
}
- node = NewSubstring(CordRep::Ref(node), start, len);
+ node = CordRepSubstring::Create(CordRep::Ref(node), start, len);
}
while (!lhs_stack.empty()) {
node = Concat(CordRep::Ref(lhs_stack.back()), node);
@@ -768,7 +751,7 @@ static CordRep* NewSubRange(CordRep* node, size_t pos, size_t n) {
pos += node->substring()->start;
node = node->substring()->child;
}
- results.push_back(NewSubstring(CordRep::Ref(node), pos, n));
+ results.push_back(CordRepSubstring::Create(CordRep::Ref(node), pos, n));
}
} while (!todo.empty());
assert(results.size() == 1);
@@ -1157,12 +1140,7 @@ Cord Cord::ChunkIterator::AdvanceAndReadBytes(size_t n) {
: payload->flat()->Data();
const size_t offset = current_chunk_.data() - data;
- CordRepSubstring* tree = new CordRepSubstring();
- tree->tag = cord_internal::SUBSTRING;
- tree->length = n;
- tree->start = offset;
- tree->child = CordRep::Ref(payload);
-
+ auto* tree = CordRepSubstring::Create(CordRep::Ref(payload), offset, n);
subcord.contents_.EmplaceTree(VerifyTree(tree), method);
bytes_remaining_ -= n;
current_chunk_.remove_prefix(n);
diff --git a/absl/strings/cord_test.cc b/absl/strings/cord_test.cc
index 9dcc4ce5..f69209de 100644
--- a/absl/strings/cord_test.cc
+++ b/absl/strings/cord_test.cc
@@ -56,6 +56,7 @@ using absl::cord_internal::CordRepCrc;
using absl::cord_internal::CordRepExternal;
using absl::cord_internal::CordRepFlat;
using absl::cord_internal::CordRepSubstring;
+using absl::cord_internal::CordzUpdateTracker;
using absl::cord_internal::kFlatOverhead;
using absl::cord_internal::kMaxFlatLength;
@@ -212,14 +213,9 @@ class CordTestPeer {
ABSL_RAW_CHECK(src.ExpectedChecksum() == absl::nullopt,
"Can not be hardened");
Cord cord;
- auto* rep = new cord_internal::CordRepSubstring;
- rep->tag = cord_internal::SUBSTRING;
- rep->child = cord_internal::CordRep::Ref(
- cord_internal::SkipCrcNode(src.contents_.tree()));
- rep->start = offset;
- rep->length = length;
- cord.contents_.EmplaceTree(rep,
- cord_internal::CordzUpdateTracker::kSubCord);
+ auto* tree = cord_internal::SkipCrcNode(src.contents_.tree());
+ auto* rep = CordRepSubstring::Create(CordRep::Ref(tree), offset, length);
+ cord.contents_.EmplaceTree(rep, CordzUpdateTracker::kSubCord);
return cord;
}
};
@@ -645,15 +641,6 @@ TEST_P(CordTest, TryFlatSubstrExternal) {
EXPECT_EQ(sub.TryFlat(), "ell");
}
-TEST_P(CordTest, TryFlatSubstrConcat) {
- absl::Cord c = absl::MakeFragmentedCord({"hello", " world"});
- absl::Cord sub = absl::CordTestPeer::MakeSubstring(c, 1, c.size() - 1);
- MaybeHarden(sub);
- EXPECT_EQ(sub.TryFlat(), absl::nullopt);
- c.RemovePrefix(1);
- EXPECT_EQ(c.TryFlat(), absl::nullopt);
-}
-
TEST_P(CordTest, TryFlatCommonlyAssumedInvariants) {
// The behavior tested below is not part of the API contract of Cord, but it's
// something we intend to be true in our current implementation. This test
diff --git a/absl/strings/internal/cord_internal.cc b/absl/strings/internal/cord_internal.cc
index 06119350..b6b06cfa 100644
--- a/absl/strings/internal/cord_internal.cc
+++ b/absl/strings/internal/cord_internal.cc
@@ -17,11 +17,13 @@
#include <cassert>
#include <memory>
+#include "absl/base/internal/raw_logging.h"
#include "absl/container/inlined_vector.h"
#include "absl/strings/internal/cord_rep_btree.h"
#include "absl/strings/internal/cord_rep_crc.h"
#include "absl/strings/internal/cord_rep_flat.h"
#include "absl/strings/internal/cord_rep_ring.h"
+#include "absl/strings/str_cat.h"
namespace absl {
ABSL_NAMESPACE_BEGIN
@@ -33,6 +35,11 @@ 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: ",
+ static_cast<int>(rep->tag)));
+}
+
void CordRep::Destroy(CordRep* rep) {
assert(rep != nullptr);
diff --git a/absl/strings/internal/cord_internal.h b/absl/strings/internal/cord_internal.h
index 8db6aa6d..ece3db15 100644
--- a/absl/strings/internal/cord_internal.h
+++ b/absl/strings/internal/cord_internal.h
@@ -21,6 +21,7 @@
#include <cstdint>
#include <type_traits>
+#include "absl/base/attributes.h"
#include "absl/base/config.h"
#include "absl/base/internal/endian.h"
#include "absl/base/internal/invoke.h"
@@ -33,6 +34,19 @@ namespace absl {
ABSL_NAMESPACE_BEGIN
namespace cord_internal {
+// The overhead of a vtable is too much for Cord, so we roll our own subclasses
+// using only a single byte to differentiate classes from each other - the "tag"
+// byte. Define the subclasses first so we can provide downcasting helper
+// functions in the base class.
+struct CordRep;
+struct CordRepConcat;
+struct CordRepExternal;
+struct CordRepFlat;
+struct CordRepSubstring;
+struct CordRepCrc;
+class CordRepRing;
+class CordRepBtree;
+
class CordzInfo;
// Default feature enable states for cord ring buffers
@@ -74,6 +88,9 @@ enum Constants {
kMaxBytesToCopy = 511
};
+// Emits a fatal error "Unexpected node type: xyz" and aborts the program.
+ABSL_ATTRIBUTE_NORETURN void LogFatalNodeType(CordRep* rep);
+
// Compact class for tracking the reference count and state flags for CordRep
// instances. Data is stored in an atomic int32_t for compactness and speed.
class RefcountAndFlags {
@@ -156,19 +173,6 @@ class RefcountAndFlags {
std::atomic<int32_t> count_;
};
-// The overhead of a vtable is too much for Cord, so we roll our own subclasses
-// using only a single byte to differentiate classes from each other - the "tag"
-// byte. Define the subclasses first so we can provide downcasting helper
-// functions in the base class.
-
-struct CordRepConcat;
-struct CordRepExternal;
-struct CordRepFlat;
-struct CordRepSubstring;
-struct CordRepCrc;
-class CordRepRing;
-class CordRepBtree;
-
// Various representations that we allow
enum CordRepKind {
UNUSED_0 = 0,
@@ -276,6 +280,12 @@ struct CordRep {
struct CordRepSubstring : public CordRep {
size_t start; // Starting offset of substring in child
CordRep* child;
+
+ // Creates a substring on `child`, adopting a reference on `child`.
+ // Requires `child` to be either a flat or external node, and `pos` and `n` to
+ // form a non-empty partial sub range of `'child`, i.e.:
+ // `n > 0 && n < length && n + pos <= length`
+ static inline CordRepSubstring* Create(CordRep* child, size_t pos, size_t n);
};
// Type for function pointer that will invoke the releaser function and also
@@ -339,6 +349,28 @@ struct CordRepExternalImpl
}
};
+inline CordRepSubstring* CordRepSubstring::Create(CordRep* child, size_t pos,
+ size_t n) {
+ assert(child != nullptr);
+ assert(n > 0);
+ assert(n < child->length);
+ assert(pos < child->length);
+ assert(n <= child->length - pos);
+
+ // TODO(b/217376272): Harden internal logic.
+ // Move to strategical places inside the Cord logic and make this an assert.
+ if (ABSL_PREDICT_FALSE(!(child->IsExternal() || child->IsFlat()))) {
+ LogFatalNodeType(child);
+ }
+
+ CordRepSubstring* rep = new CordRepSubstring();
+ rep->length = n;
+ rep->tag = SUBSTRING;
+ rep->start = pos;
+ rep->child = child;
+ return rep;
+}
+
inline void CordRepExternal::Delete(CordRep* rep) {
assert(rep != nullptr && rep->IsExternal());
auto* rep_external = static_cast<CordRepExternal*>(rep);
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-18 19:43:31 +0000