Http Client API

api/include/opentelemetry/http/http_client.h

@@ -0,0 +1,161 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#pragma once
+
+#include "opentelemetry/nostd/string_view.h"
+
+OPENTELEMETRY_BEGIN_NAMESPACE
+namespace http
+{
+
+enum class HttpResult : uint8_t
+{
+  // Response has been received successfully from target server.
+  HttpResult_OK = 0,
+
+  // Request has been aborted by the caller. The server might or
+  // might not have already received or processed the request.
+  HttpResult_Aborted = 1,
+
+  // Local conditions have prevented the request from being sent
+  // (invalid request parameters, out of memory, internal error etc.)
+  HttpResult_LocalFailure = 2,
+
+  // Network conditions somewhere between the local machine and
+  // the target server have caused the request to fail
+  // (connection failed, connection dropped abruptly etc.).
+  HttpResult_NetworkFailure = 3
+
+};
+
+// The HttpHeaders class contains a set of HTTP headers.
+class HttpHeaders
+{
+public:
+  // Inserts a name/value pair, and removes elements with the same name.
+  virtual void set(nostd::string_view const &name, nostd::string_view const &value) = 0;
+
+  // Inserts a name/value pair
+  virtual void add(nostd::string_view const &name, nostd::string_view const &value) = 0;
+
+  // Gets a string value given a name
+  // Returns:
+  //      If there are multiple headers with same name, it returns any one of the value
+  //      (implementation defined) Empty string if there is no header with speicfied name..
+  virtual nostd::string_view const &get(nostd::string_view const &name) const = 0;
+
+  // Tests whether the headers contain the specified name.
+  virtual bool contains(nostd::string_view const &name) const = 0;
+};
+
+// The HttpRequest class represents a Request object.
+// Individual HTTP client implementations can implement the request object in
+// the most efficient way. Either fill the request first, and then issue
+// the underlying request, or create the real request immediately, and then forward
+// the methods and set the individual parameters directly one by one.
+class HttpRequest
+{
+public:
+  // Gets the request ID.
+  virtual const nostd::string_view &GetId() const = 0;
+
+  // Sets the request Method
+  virtual void SetMethod(nostd::string_view const &method) = 0;
+
+  // Gets the request URI
+  virtual void SetUrl(nostd::string_view const &url) = 0;
+
+  // Gets the request Headers
+  virtual HttpHeaders &GetHeaders() const = 0;
+
+  // Sets the request body
+  virtual void SetBody(const uint8_t *const body, const size_t len) = 0;
+
+  // Gets the request body
+  virtual void GetBody(uint8_t *body, size_t &len) = 0;
+};
+
+// The HttpResponse class represents a Response object.
+// Individual HTTP client implementations can implement the response object
+// in the most efficient way. Either copy all of the underlying data to a new
+// structure, and provide it to the callback; or keep the real
+// response data around, forward the methods, and retrieve the individual
+// values directly one by one.
+class HttpResponse
+{
+public:
+  // Gets the response ID.
+  virtual const nostd::string_view &GetId() = 0;
+
+  // Get the response result code.
+  virtual HttpResult GetResult() = 0;
+
+  // Gets the response status code.
+  virtual unsigned GetStatusCode() = 0;
+
+  // Gets the response headers.
+  virtual const HttpHeaders &GetHeaders() = 0;
+
+  // Gets the response body.
+  virtual void GetBody(uint8_t *body, size_t &len) = 0;
+};
+
+// The HttpResponseCallback class receives HTTP client responses
+class HttpResponseCallback
+{
+public:
+  // Called when an HTTP request completes.
+  // The passed response object contains details about the exact way the
+  // request finished (HTTP status code, headers, content, error codes
+  // etc.). The ownership of the response object is transferred to the
+  // callback object. It can store it for later if necessary. Finally, it
+  // must be deleted using its virtual destructor.
+  virtual void OnHttpResponse(HttpResponse *response) = 0;
+};
+
+// The HttpClient class is the interface for HTTP client implementations.
+class HttpClient
+{
+public:
+  // Creates an empty HTTP request object.
+  // The created request object has only its ID prepopulated. Other fields
+  // must be set by the caller. The request object can then be sent
+  // using SendRequestAsync(). If you are not going to use the request object
+  // then you can delete it safely using its virtual destructor.
+  virtual HttpRequest *CreateRequest() = 0;
+
+  // Begins an HTTP request.
+  // The method takes ownership of the passed request, and can destroy it before
+  // returning to the caller. Do not access the request object in any
+  // way after this invocation, and do not delete it.
+  // The callback object is always called, even if the request is
+  // cancelled, or if an error occurs immediately during sending. In the
+  // latter case, the OnHttpResponse() callback is called before this
+  // method returns. You must keep the callback object alive until its
+  // OnHttpResponse() callback is called.
+  virtual void SendRequest(HttpRequest *request, HttpResponseCallback *callback) = 0;
+
+  // Cancels an HTTP request.
+  // The caller must provide a string ID returned earlier by request->GetId().
+  // The request is cancelled asynchronously. The caller must still
+  // wait for the relevant OnHttpResponse() callback (it can just come
+  // earlier with some "aborted" error status).
+  virtual void CancelRequest(nostd::string_view const &id) = 0;
+
+  virtual void CancelAllRequestsSync() {}
+};
+
+}  // namespace http
+OPENTELEMETRY_END_NAMESPACE

sdk/include/opentelemetry/sdk/http/http_client.h

@@ -0,0 +1,153 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#pragma once
+#include "opentelemetry/http/http_client.h"
+#include "opentelemetry/version.h"
+
+#include <algorithm>
+#include <cstring>
+#include <functional>
+#include <map>
+#include <memory>
+#include <vector>
+
+OPENTELEMETRY_BEGIN_NAMESPACE
+namespace sdk
+{
+namespace http
+{
+namespace http_api = opentelemetry::http;
+
+static std::function<bool(const std::string &, const std::string &)> CaseInsensitiveComparator =
+    [](const std::string &s1, const std::string &s2) -> bool {
+  std::string str1(s1.length(), ' ');
+  std::string str2(s2.length(), ' ');
+  auto lowerCase = [](char c) -> char { return tolower(c); };
+  std::transform(s1.begin(), s1.end(), str1.begin(), lowerCase);
+  std::transform(s2.begin(), s2.end(), str2.begin(), lowerCase);
+  return str1 < str2;
+};
+
+// HttpHeaders implementation
+class HttpHeaders : http_api::HttpHeaders,
+                    std::multimap<std::string, std::string, decltype(CaseInsensitiveComparator)>
+{
+public:
+  virtual void set(nostd::string_view const &name, nostd::string_view const &value) override
+  {
+    auto range = equal_range(std::string(name.data()));
+    auto hint  = erase(range.first, range.second);
+    insert(hint, std::make_pair(name, value));
+  }
+
+  virtual void add(nostd::string_view const &name, nostd::string_view const &value) override
+  {
+    insert(std::make_pair(name, value));
+  }
+
+  virtual nostd::string_view const &get(nostd::string_view const &name) const override
+  {
+    auto it = find(std::string(name.data()));
+    return (it != end()) ? it->second : m_empty;
+  }
+
+  virtual bool contains(nostd::string_view const &name) const override
+  {
+    auto it = find(std::string(name.data()));
+    return (it != end());
+  }
+
+private:
+  nostd::string_view m_empty{};
+};
+
+class SimpleHttpRequest : public http_api::HttpRequest
+{
+
+public:
+  SimpleHttpRequest(nostd::string_view const &id) : id_(id), method_("GET") {}
+
+  // Gets the HTTP request ID.
+  virtual const nostd::string_view &GetId() const override { return id_; }
+
+  // Sets the request method
+  virtual void SetMethod(nostd::string_view const &method) override { method_ = method; }
+
+  // Sets the HTTP request URI.
+  virtual void SetUrl(nostd::string_view const &url) override { url_ = url; }
+
+  // Gets the HTTP request headers.
+  virtual http_api::HttpHeaders &GetHeaders() const override { return *headers_; }
+
+  // Sets the request body.
+  virtual void SetBody(const uint8_t *const body, const size_t len) override
+  {
+    for (int i = 0; i < len; i++)
+    {
+      body_.push_back(body[i]);
+    }
+  }
+
+  virtual void GetBody(uint8_t *body, size_t &len) override
+  {
+    len = 0;
+    for (auto &e : body_)
+    {
+      body[len++] = e;
+    }
+    len = (len > 0) ? len - 1 : len;
+  }
+
+private:
+  std::unique_ptr<http_api::HttpHeaders> headers_;
+  std::vector<uint8_t> body_;
+  nostd::string_view method_;
+  nostd::string_view id_;
+  nostd::string_view url_;
+};
+
+class SimpleHttpResponse : public http_api::HttpResponse
+{
+
+public:
+  SimpleHttpResponse(nostd::string_view const &id)
+      : id_(id), result_(http_api::HttpResult::HttpResult_LocalFailure), statusCode_(0)
+  {}
+
+  virtual http_api::HttpResult GetResult() override { return result_; }
+
+  virtual unsigned GetStatusCode() override { return statusCode_; }
+
+  virtual const http_api::HttpHeaders &GetHeaders() override { return *headers_; }
+
+  virtual void GetBody(uint8_t *body, size_t &len) override
+  {
+    int i = 0;
+    for (auto &e : body_)
+    {
+      body_[i++] = e;
+    }
+  }
+
+private:
+  nostd::string_view id_;
+  unsigned statusCode_;
+  std::unique_ptr<http_api::HttpHeaders> headers_;
+  http_api::HttpResult result_;
+  std::vector<uint8_t> body_;
+};
+}  // namespace http
+}  // namespace sdk
+OPENTELEMETRY_END_NAMESPACE