Add connection context that will serve us as an interface between command handler and the service

server/reply_builder.cc

@@ -0,0 +1,99 @@
+// Copyright 2021, Beeri 15.  All rights reserved.
+// Author: Roman Gershman (romange@gmail.com)
+//
+#include "server/reply_builder.h"
+
+#include <absl/strings/numbers.h>
+#include <absl/strings/str_cat.h>
+
+#include "base/logging.h"
+
+using namespace std;
+using absl::StrAppend;
+
+namespace dfly {
+
+namespace {
+
+inline iovec constexpr IoVec(std::string_view s) {
+  iovec r{const_cast<char*>(s.data()), s.size()};
+  return r;
+}
+
+constexpr char kCRLF[] = "\r\n";
+constexpr char kErrPref[] = "-ERR ";
+constexpr char kSimplePref[] = "+";
+
+}  // namespace
+
+RespSerializer::RespSerializer(io::Sink* stream) : sink_(stream) {
+}
+
+void RespSerializer::Send(const iovec* v, uint32_t len) {
+  error_code ec = sink_->Write(v, len);
+  if (ec) {
+    ec_ = ec;
+  }
+}
+
+void RespSerializer::SendDirect(std::string_view raw) {
+  iovec v = {IoVec(raw)};
+
+  Send(&v, 1);
+}
+
+void ReplyBuilder::SendBulkString(std::string_view str) {
+  char tmp[absl::numbers_internal::kFastToBufferSize + 3];
+  tmp[0] = '$';  // Format length
+  char* next = absl::numbers_internal::FastIntToBuffer(uint32_t(str.size()), tmp + 1);
+  *next++ = '\r';
+  *next++ = '\n';
+
+  std::string_view lenpref{tmp, size_t(next - tmp)};
+
+  // 3 parts: length, string and CRLF.
+  iovec v[3] = {IoVec(lenpref), IoVec(str), IoVec(kCRLF)};
+
+  return Send(v, ABSL_ARRAYSIZE(v));
+}
+
+void ReplyBuilder::SendError(std::string_view str) {
+  if (str[0] == '-') {
+    iovec v[] = {IoVec(str), IoVec(kCRLF)};
+    return Send(v, ABSL_ARRAYSIZE(v));
+  } else {
+    iovec v[] = {IoVec(kErrPref), IoVec(str), IoVec(kCRLF)};
+    return Send(v, ABSL_ARRAYSIZE(v));
+  }
+}
+
+void ReplyBuilder::SendError(OpStatus status) {
+  switch (status) {
+    case OpStatus::OK:
+      SendOk();
+      break;
+    case OpStatus::KEY_NOTFOUND:
+      SendError("no such key");
+      break;
+    default:
+      LOG(ERROR) << "Unsupported status " << status;
+      SendError("Internal error");
+      break;
+  }
+}
+
+void ReplyBuilder::SendNull() {
+  constexpr char kNullStr[] = "$-1\r\n";
+
+  iovec v[] = {IoVec(kNullStr)};
+
+  Send(v, ABSL_ARRAYSIZE(v));
+}
+
+void ReplyBuilder::SendSimpleString(std::string_view str) {
+  iovec v[3] = {IoVec(kSimplePref), IoVec(str), IoVec(kCRLF)};
+
+  Send(v, ABSL_ARRAYSIZE(v));
+}
+
+}  // namespace dfly