Add user-configurable timeout to wasm http requests

Author: ianthomas23

CMakeLists.txt

@@ -98,6 +98,7 @@ set(GIT2CPP_SRC
     ${GIT2CPP_SOURCE_DIR}/utils/progress.hpp
     ${GIT2CPP_SOURCE_DIR}/utils/terminal_pager.cpp
     ${GIT2CPP_SOURCE_DIR}/utils/terminal_pager.hpp
+    ${GIT2CPP_SOURCE_DIR}/wasm/constants.hpp
     ${GIT2CPP_SOURCE_DIR}/wasm/libgit2_internals.cpp
     ${GIT2CPP_SOURCE_DIR}/wasm/libgit2_internals.hpp
     ${GIT2CPP_SOURCE_DIR}/wasm/response.cpp
@@ -110,6 +111,8 @@ set(GIT2CPP_SRC
     ${GIT2CPP_SOURCE_DIR}/wasm/subtransport.hpp
     ${GIT2CPP_SOURCE_DIR}/wasm/transport.cpp
     ${GIT2CPP_SOURCE_DIR}/wasm/transport.hpp
+    ${GIT2CPP_SOURCE_DIR}/wasm/utils.cpp
+    ${GIT2CPP_SOURCE_DIR}/wasm/utils.hpp
     ${GIT2CPP_SOURCE_DIR}/wrapper/annotated_commit_wrapper.cpp
     ${GIT2CPP_SOURCE_DIR}/wrapper/annotated_commit_wrapper.hpp
     ${GIT2CPP_SOURCE_DIR}/wrapper/branch_wrapper.cpp

src/wasm/constants.hpp

@@ -0,0 +1,11 @@
+#pragma once
+
+#include <string_view>
+
+// Constants used in wasm transport layer.
+// Exposed to non-emscripten builds so that they can be used in help.
+
+// Environment variable for http transport timeout.
+// Must be a positive number as a timeout of 0 will block forever.
+inline constexpr std::string_view WASM_HTTP_TRANSPORT_TIMEOUT_NAME = "GIT_HTTP_TIMEOUT";
+inline constexpr unsigned int WASM_HTTP_TRANSPORT_TIMEOUT_DEFAULT = 10;

src/wasm/stream.cpp

@@ -44,6 +44,7 @@ EM_JS(
      const char* method,
      const char* content_type_header,
      const char* authorization_header,
+     unsigned long request_timeout_ms,
      size_t buffer_size),
     {
         const url_js = UTF8ToString(url);
@@ -65,6 +66,7 @@ EM_JS(
                 // Should this only be set if using https?  What about CORS via http?
                 xhr.setRequestHeader("Authorization", authorization_header_js);
             }
+            xhr.timeout = request_timeout_ms;
 
             // Cache request info on JavaScript side so that it is available in subsequent calls
             // without having to pass it back and forth to/from C++.
@@ -257,6 +259,7 @@ static int create_request(wasm_http_stream* stream, std::string_view content_hea
         name_for_method(stream->m_service.m_method).c_str(),
         content_header.data(),
         stream->m_subtransport->m_authorization_header.c_str(),
+        stream->m_subtransport->m_request_timeout_ms,
         EMFORGE_BUFSIZE
     );
     return stream->m_request_index;

src/wasm/subtransport.cpp

@@ -2,15 +2,16 @@
 
 #    include "subtransport.hpp"
 
+#    include <iostream>
 #    include <regex>
 #    include <sstream>
 
-#    include <emscripten.h>
 #    include <git2/sys/credential.h>
 #    include <git2/sys/remote.h>
 
 #    include "libgit2_internals.hpp"
 #    include "stream.hpp"
+#    include "utils.hpp"
 
 // C functions.
 
@@ -93,6 +94,7 @@ int create_wasm_http_subtransport(git_smart_subtransport** out, git_transport* o
     subtransport->m_owner = owner;
     subtransport->m_base_url = "";
     subtransport->m_credential = nullptr;
+    subtransport->m_request_timeout_ms = get_request_timeout_ms();
 
     *out = &subtransport->m_parent;
     return 0;

src/wasm/subtransport.hpp

@@ -17,7 +17,8 @@ struct wasm_http_subtransport
     // Data stored for reuse on other streams of this transport:
     std::string m_base_url;
     std::string m_authorization_header;
-    git_credential* m_credential;  // libgit2 creates this, we are responsible for deleting it.
+    git_credential* m_credential;        // libgit2 creates this, we are responsible for deleting it.
+    unsigned long m_request_timeout_ms;  // Timeout for http(s) requests in milliseconds.
 };
 
 // git_smart_subtransport_cb

src/wasm/utils.cpp

@@ -0,0 +1,38 @@
+#ifdef EMSCRIPTEN
+
+#    include "utils.hpp"
+
+#    include <termcolor/termcolor.hpp>
+
+#    include "constants.hpp"
+
+unsigned long get_request_timeout_ms()
+{
+    double timeout_seconds = WASM_HTTP_TRANSPORT_TIMEOUT_DEFAULT;
+    auto env_var = std::getenv(WASM_HTTP_TRANSPORT_TIMEOUT_NAME.data());
+    if (env_var != nullptr)
+    {
+        try
+        {
+            auto value = std::stod(env_var);
+            if (value <= 0)
+            {
+                throw std::runtime_error("negative or zero");
+            }
+            timeout_seconds = value;
+        }
+        catch (std::exception& e)
+        {
+            // Catch failures from (1) stod and (2) timeout <= 0.
+            // Print warning and use default value.
+            std::cout << termcolor::yellow << "Warning: environment variable "
+                      << WASM_HTTP_TRANSPORT_TIMEOUT_NAME
+                      << " must be a positive number of seconds, using default value of "
+                      << WASM_HTTP_TRANSPORT_TIMEOUT_DEFAULT << " seconds instead." << termcolor::reset
+                      << std::endl;
+        }
+    }
+    return 1000 * timeout_seconds;
+}
+
+#endif  // EMSCRIPTEN

src/wasm/utils.hpp

@@ -0,0 +1,8 @@
+#pragma once
+
+#ifdef EMSCRIPTEN
+
+// Get wasm http request timeout in milliseconds from environment variable or default value.
+unsigned long get_request_timeout_ms();
+
+#endif  // EMSCRIPTEN