Replaced the underlying zlib/deflate implementation with the actual zstd library

zstd_image_transport/CMakeLists.txt

@@ -16,20 +16,20 @@ find_package(image_transport REQUIRED)
 find_package(pluginlib REQUIRED)
 find_package(rclcpp REQUIRED)
 find_package(sensor_msgs REQUIRED)
-find_package(ZLIB REQUIRED)
+find_package(zstd REQUIRED)
 
 include_directories(include)
 
 add_library(
   ${PROJECT_NAME} SHARED
-  src/zlib_cpp.cpp
+  src/zstd_wrapper.cpp
   src/zstd_publisher.cpp
   src/zstd_subscriber.cpp
   src/manifest.cpp
 )
 
 target_link_libraries(${PROJECT_NAME}
-  ZLIB::ZLIB
+  zstd::libzstd_shared
   image_transport::image_transport
   rclcpp::rclcpp
   pluginlib::pluginlib

zstd_image_transport/include/zstd_image_transport/zstd_publisher.hpp

@@ -31,6 +31,7 @@
 #ifndef ZSTD_IMAGE_TRANSPORT__ZSTD_PUBLISHER_HPP_
 #define ZSTD_IMAGE_TRANSPORT__ZSTD_PUBLISHER_HPP_
 
+#include <memory>
 #include <string>
 #include <vector>
 #include <unordered_set>
@@ -44,6 +45,9 @@
 
 #include "zstd_image_transport/zstd_common.hpp"
 
+// Forward declaration — defined in the private zstd_wrapper.hpp header.
+namespace zstd_wrapper {class Compressor;}
+
 namespace zstd_image_transport
 {
 
@@ -70,6 +74,9 @@ class ZstdPublisher : public image_transport::SimplePublisherPlugin<CompressedIm
   rclcpp::node_interfaces::NodeParametersInterface::SharedPtr node_param_interface_;
   rclcpp::node_interfaces::NodeBaseInterface::SharedPtr node_base_interface_;
 
+  // Reusable compression context — avoids per-frame ZSTD_CCtx allocation.
+  mutable std::unique_ptr<zstd_wrapper::Compressor> compressor_;
+
 private:
   std::vector<std::string> parameters_;
   std::unordered_set<std::string> deprecated_parameters_;

zstd_image_transport/include/zstd_image_transport/zstd_subscriber.hpp

@@ -31,6 +31,7 @@
 #ifndef ZSTD_IMAGE_TRANSPORT__ZSTD_SUBSCRIBER_HPP_
 #define ZSTD_IMAGE_TRANSPORT__ZSTD_SUBSCRIBER_HPP_
 
+#include <memory>
 #include <string>
 #include <vector>
 
@@ -44,6 +45,9 @@
 
 #include "zstd_image_transport/zstd_common.hpp"
 
+// Forward declaration — defined in the private zstd_wrapper.hpp header.
+namespace zstd_wrapper {class Decompressor;}
+
 namespace zstd_image_transport
 {
 
@@ -67,6 +71,9 @@ class ZstdSubscriber final
     const Callback & user_cb) override;
 
   rclcpp::Logger logger_;
+
+  // Reusable decompression context — avoids per-frame ZSTD_DCtx allocation.
+  std::unique_ptr<zstd_wrapper::Decompressor> decompressor_;
 };
 
 }  // namespace zstd_image_transport

zstd_image_transport/package.xml

@@ -14,7 +14,7 @@
   <buildtool_depend>ament_cmake</buildtool_depend>
 
   <depend>image_transport</depend>
-  <depend>zlib</depend>
+  <depend>libzstd-dev</depend>
 
   <test_depend>ament_lint_auto</test_depend>
   <test_depend>ament_lint_common</test_depend>

zstd_image_transport/src/zstd_publisher.cpp

@@ -31,7 +31,7 @@
 
 #include <rclcpp/rclcpp.hpp>
 
-#include "zlib_cpp.hpp"
+#include "zstd_wrapper.hpp"
 
 namespace zstd_image_transport
 {
@@ -97,23 +97,19 @@ void ZstdPublisher::publish(
   const sensor_msgs::msg::Image & message,
   const PublisherT & publisher) const
 {
-  // Fresh Configuration
   int cfg_zstd_level =
     node_param_interface_->get_parameter(
       parameters_[ZSTD_LEVEL]).as_int();
 
-  zlib::Comp comp(static_cast<zlib::Comp::Level>(cfg_zstd_level), true);
-  auto g_compressed_data =
-    comp.Process(&message.data[0], message.data.size(), true);
-
-  size_t total_size = 0;
-  for (const auto & data : g_compressed_data) {
-    total_size += data->size;
+  // Lazily initialize the reusable compression context.
+  if (!compressor_) {
+    compressor_ = std::make_unique<zstd_wrapper::Compressor>();
   }
 
   auto compressed = std::make_unique<sensor_msgs::msg::CompressedImage>();
 
-  int metadata = 4 + 4 + 1 + 4 + 4 + message.encoding.size();
+  sensor_msgs::msg::CompressedImage compressed;
+  compressed.data.resize(metadata + bound);
 
   compressed->data.resize(total_size + metadata);