Use StringBuilder in TlStorerToString to speed up it 2 times.

tdutils/td/utils/TlStorerToString.h

@@ -9,101 +9,72 @@
 #include "td/utils/common.h"
 #include "td/utils/SharedSlice.h"
 #include "td/utils/Slice.h"
-#include "td/utils/SliceBuilder.h"
+#include "td/utils/StackAllocator.h"
+#include "td/utils/StringBuilder.h"
 #include "td/utils/UInt.h"
 
 namespace td {
 
 class TlStorerToString {
-  string result;
-  size_t shift = 0;
+  decltype(StackAllocator::alloc(0)) buffer_ = StackAllocator::alloc(1 << 14);
+  StringBuilder sb_ = StringBuilder(buffer_.as_slice(), true);
+  size_t shift_ = 0;
 
   void store_field_begin(const char *name) {
-    result.append(shift, ' ');
+    sb_.append_char(shift_, ' ');
     if (name && name[0]) {
-      result += name;
-      result += " = ";
+      sb_ << name << " = ";
     }
   }
 
   void store_field_end() {
-    result += '\n';
-  }
-
-  void store_long(int64 value) {
-    result += (PSLICE() << value).c_str();
+    sb_.push_back('\n');
   }
 
   void store_binary(Slice data) {
     static const char *hex = "0123456789ABCDEF";
 
-    result.append("{ ", 2);
+    sb_ << "{ ";
     for (auto c : data) {
       unsigned char byte = c;
-      result += hex[byte >> 4];
-      result += hex[byte & 15];
-      result += ' ';
+      sb_.push_back(hex[byte >> 4]);
+      sb_.push_back(hex[byte & 15]);
+      sb_.push_back(' ');
     }
-    result += '}';
+    sb_.push_back('}');
   }
 
  public:
   TlStorerToString() = default;
   TlStorerToString(const TlStorerToString &) = delete;
   TlStorerToString &operator=(const TlStorerToString &) = delete;
-
-  void store_field(const char *name, bool value) {
-    store_field_begin(name);
-    result += (value ? "true" : "false");
-    store_field_end();
-  }
-
-  void store_field(const char *name, int32 value) {
-    store_field(name, static_cast<int64>(value));
-  }
-
-  void store_field(const char *name, int64 value) {
-    store_field_begin(name);
-    store_long(value);
-    store_field_end();
-  }
-
-  void store_field(const char *name, double value) {
-    store_field_begin(name);
-    result += (PSLICE() << value).c_str();
-    store_field_end();
-  }
-
-  void store_field(const char *name, const char *value) {
-    store_field_begin(name);
-    result += value;
-    store_field_end();
-  }
+  TlStorerToString(TlStorerToString &&) = delete;
+  TlStorerToString &operator=(TlStorerToString &&) = delete;
 
   void store_field(const char *name, const string &value) {
     store_field_begin(name);
-    result += '"';
-    result += value;
-    result += '"';
+    sb_.push_back('"');
+    sb_ << value;
+    sb_.push_back('"');
     store_field_end();
   }
 
   void store_field(const char *name, const SecureString &value) {
     store_field_begin(name);
-    result.append("<secret>");
+    sb_ << "<secret>";
     store_field_end();
   }
 
   template <class T>
   void store_field(const char *name, const T &value) {
     store_field_begin(name);
-    result.append(value.data(), value.size());
+    sb_ << value;
     store_field_end();
   }
 
   void store_bytes_field(const char *name, const SecureString &value) {
     store_field_begin(name);
-    result.append("<secret>");
+    sb_ << "<secret>";
     store_field_end();
   }
 
@@ -112,27 +83,25 @@ class TlStorerToString {
     static const char *hex = "0123456789ABCDEF";
 
     store_field_begin(name);
-    result.append("bytes [");
-    store_long(static_cast<int64>(value.size()));
-    result.append("] { ");
+    sb_ << "bytes [" << value.size() << "] { ";
     size_t len = min(static_cast<size_t>(64), value.size());
     for (size_t i = 0; i < len; i++) {
       int b = value[static_cast<int>(i)] & 0xff;
-      result += hex[b >> 4];
-      result += hex[b & 15];
-      result += ' ';
+      sb_.push_back(hex[b >> 4]);
+      sb_.push_back(hex[b & 15]);
+      sb_.push_back(' ');
     }
     if (len < value.size()) {
-      result.append("...");
+      sb_ << "...";
     }
-    result += '}';
+    sb_.push_back('}');
     store_field_end();
   }
 
   template <class ObjectT>
   void store_object_field(const char *name, const ObjectT *value) {
     if (value == nullptr) {
-      store_field(name, "null");
+      store_field(name, Slice("null"));
     } else {
       value->store(*this, name);
     }
@@ -152,28 +121,25 @@ class TlStorerToString {
 
   void store_vector_begin(const char *field_name, size_t vector_size) {
     store_field_begin(field_name);
-    result += "vector[";
-    result += (PSLICE() << vector_size).c_str();
-    result += "] {\n";
-    shift += 2;
+    sb_ << "vector[" << vector_size << "] {\n";
+    shift_ += 2;
   }
 
   void store_class_begin(const char *field_name, const char *class_name) {
     store_field_begin(field_name);
-    result += class_name;
-    result += " {\n";
-    shift += 2;
+    sb_ << class_name << " {\n";
+    shift_ += 2;
   }
 
   void store_class_end() {
-    CHECK(shift >= 2);
-    shift -= 2;
-    result.append(shift, ' ');
-    result += "}\n";
+    CHECK(shift_ >= 2);
+    shift_ -= 2;
+    sb_.append_char(shift_, ' ');
+    sb_ << "}\n";
   }
 
   string move_as_string() {
-    return std::move(result);
+    return sb_.as_cslice().str();
   }
 };