Export of internal Abseil changes

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9fc37c11b9e46287acef00ee06ed9adcba54dd13 by Greg Falcon <gfalcon@google.com>:

Rename absl::hash_internal::HashState to absl::hash_internal::MixingHashState.

Before this change, we had two classes named HashState: absl::HashState, the public API used for type erasure, and absl::hash_internal::HashState, the internal concrete implementation ordinarily used.

The internal class used to be named `CityHashState`, but we renamed it to `HashState` it when we changed underlying hash implementation to wyhash.  This inadvertent naming conflict made the code much harder to read, and this change intends to undo that.

PiperOrigin-RevId: 373481959

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4aec55ffddebd085c239352a2e20721091f719a1 by Greg Falcon <gfalcon@google.com>:

Introduce absl::HashOf(), a convenience wrapper around absl::Hash that calculates hashes from the values of its arguments.

PiperOrigin-RevId: 373461406

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86b5fd8db50bbc8bd0aa9258523527381fe0445d by Abseil Team <absl-team@google.com>:

Improve speed of BlockingCounter by making its most common path lock free.

With the new implementation, the fast path of BlockingCounter::DecrementCount()
is only a fetch_sub operation. This is most times much more efficient than the
previous implementation (full mutex lock/unlock). As a matter of fact, in most
actual usecases in practice, the waiter thread is already waiting on the
Wait() call when DecrementCount() is called, which makes Mutex::Unlock() take
the slow path as there's a waiter thread that it might need to wake up.

PiperOrigin-RevId: 373394164

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65c876be5eac0cd32583ff8535ede4109d39cf3f by Martijn Vels <mvels@google.com>:

Move the 'sample copied cord' logic into MaybeTrackCord(),

This changes move the logic for selecting if a cord should remain being sampled from Cord to CordzInfo::MaybeTrackCord, and updates the documentation for the latter method.

PiperOrigin-RevId: 373363168

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e84410bd0aada293a81dfb82656c952e209e21fb by Martijn Vels <mvels@google.com>:

Add check for the first call to cordz_should_profile() for each thread.

This prevents the first cord of a newly created thread to be always sampled, which is a 'bad' kind of determinism for sampling.

PiperOrigin-RevId: 373229768

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bf09c589dc099ac8f4af780bf7e609c53c27574c by Samuel Benzaquen <sbenza@google.com>:

Refactor the Flags structure into an enum.
This gives us more control over the representation and allows for easier
merging during parsing.

PiperOrigin-RevId: 373163038

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b947b0c51083b7b6508284b5d31819596c91729e by Derek Mauro <dmauro@google.com>:

Fixes warnings about shadowed variables
Fixes #956

PiperOrigin-RevId: 373158133
GitOrigin-RevId: 9fc37c11b9e46287acef00ee06ed9adcba54dd13
Change-Id: I91f35699f9bf439d1a870c6493946a310afe088c

1 files changed, 36 insertions, 18 deletions

diff --git a/absl/strings/internal/str_format/extension.h b/absl/strings/internal/str_format/extension.h
index a9b9e137..55cbb56d 100644
--- a/absl/strings/internal/str_format/extension.h
+++ b/absl/strings/internal/str_format/extension.h
@@ -128,19 +128,33 @@ class FormatSinkImpl {
   char buf_[1024];
 };
 
-struct Flags {
-  bool basic : 1;     // fastest conversion: no flags, width, or precision
-  bool left : 1;      // "-"
-  bool show_pos : 1;  // "+"
-  bool sign_col : 1;  // " "
-  bool alt : 1;       // "#"
-  bool zero : 1;      // "0"
-  std::string ToString() const;
-  friend std::ostream& operator<<(std::ostream& os, const Flags& v) {
-    return os << v.ToString();
-  }
+enum class Flags : uint8_t {
+  kBasic = 0,
+  kLeft = 1 << 0,
+  kShowPos = 1 << 1,
+  kSignCol = 1 << 2,
+  kAlt = 1 << 3,
+  kZero = 1 << 4,
+  // This is not a real flag. It just exists to turn off kBasic when no other
+  // flags are set. This is for when width/precision are specified.
+  kNonBasic = 1 << 5,
 };
 
+constexpr Flags operator|(Flags a, Flags b) {
+  return static_cast<Flags>(static_cast<uint8_t>(a) | static_cast<uint8_t>(b));
+}
+
+constexpr bool FlagsContains(Flags haystack, Flags needle) {
+  return (static_cast<uint8_t>(haystack) & static_cast<uint8_t>(needle)) ==
+         static_cast<uint8_t>(needle);
+}
+
+std::string FlagsToString(Flags v);
+
+inline std::ostream& operator<<(std::ostream& os, Flags v) {
+  return os << FlagsToString(v);
+}
+
 // clang-format off
 #define ABSL_INTERNAL_CONVERSION_CHARS_EXPAND_(X_VAL, X_SEP) \
   /* text */ \
@@ -257,12 +271,16 @@ struct FormatConversionSpecImplFriend;
 class FormatConversionSpecImpl {
  public:
   // Width and precison are not specified, no flags are set.
-  bool is_basic() const { return flags_.basic; }
-  bool has_left_flag() const { return flags_.left; }
-  bool has_show_pos_flag() const { return flags_.show_pos; }
-  bool has_sign_col_flag() const { return flags_.sign_col; }
-  bool has_alt_flag() const { return flags_.alt; }
-  bool has_zero_flag() const { return flags_.zero; }
+  bool is_basic() const { return flags_ == Flags::kBasic; }
+  bool has_left_flag() const { return FlagsContains(flags_, Flags::kLeft); }
+  bool has_show_pos_flag() const {
+    return FlagsContains(flags_, Flags::kShowPos);
+  }
+  bool has_sign_col_flag() const {
+    return FlagsContains(flags_, Flags::kSignCol);
+  }
+  bool has_alt_flag() const { return FlagsContains(flags_, Flags::kAlt); }
+  bool has_zero_flag() const { return FlagsContains(flags_, Flags::kZero); }
 
   FormatConversionChar conversion_char() const {
     // Keep this field first in the struct . It generates better code when
@@ -306,7 +324,7 @@ struct FormatConversionSpecImplFriend final {
     conv->precision_ = p;
   }
   static std::string FlagsToString(const FormatConversionSpecImpl& spec) {
-    return spec.flags_.ToString();
+    return str_format_internal::FlagsToString(spec.flags_);
   }
 };