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Merged
thiagoralves merged 2 commits into from
Dec 9, 2025
Merged

Optimize mutex usage to minimize hold time and prevent priority inversion #45

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3e7d427
Optimize mutex usage to minimize hold time and prevent priority inver…
devin-ai-integration[bot] Dec 7, 2025
0d82185
Add logging for failed data conversions in read operations
devin-ai-integration[bot] Dec 9, 2025
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98 changes: 67 additions & 31 deletions core/src/drivers/plugin_driver.c
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Original file line number Diff line number Diff line change
Expand Up @@ -5,11 +5,11 @@
#include "../plc_app/utils/log.h"
#include "plugin_config.h"
#include "plugin_driver.h"
#include <dlfcn.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <dlfcn.h>

// External buffer declarations from image_tables.c
extern IEC_BOOL *bool_input[BUFFER_SIZE][8];
Expand Down Expand Up @@ -41,13 +41,33 @@ plugin_driver_t *plugin_driver_create(void)
return NULL;
}

// Initialize mutex
if (pthread_mutex_init(&driver->buffer_mutex, NULL) != 0)
// Initialize mutex with priority inheritance to prevent priority inversion
// This ensures that when a lower-priority plugin thread holds the mutex,
// it temporarily inherits the priority of any higher-priority thread
// (like the PLC scan cycle thread) waiting for the mutex.
pthread_mutexattr_t mutex_attr;
if (pthread_mutexattr_init(&mutex_attr) != 0)
{
free(driver);
return NULL;
}

if (pthread_mutexattr_setprotocol(&mutex_attr, PTHREAD_PRIO_INHERIT) != 0)
{
pthread_mutexattr_destroy(&mutex_attr);
free(driver);
return NULL;
}

if (pthread_mutex_init(&driver->buffer_mutex, &mutex_attr) != 0)
{
pthread_mutexattr_destroy(&mutex_attr);
free(driver);
return NULL;
}

pthread_mutexattr_destroy(&mutex_attr);

return driver;
}

Expand Down Expand Up @@ -105,34 +125,37 @@ int plugin_driver_load_config(plugin_driver_t *driver, const char *config_file)
// Check if config file exists, if not copy from default
if (access(config_file, F_OK) != 0)
{
printf("[PLUGIN]: Config file %s not found, copying from plugins_default.conf\n", config_file);

printf("[PLUGIN]: Config file %s not found, copying from plugins_default.conf\n",
config_file);

// Check if default config exists
if (access("plugins_default.conf", F_OK) != 0)
{
printf("[PLUGIN]: Default config file plugins_default.conf not found\n");
return -1;
}

// Copy default config to target config file
FILE *src = fopen("plugins_default.conf", "r");
FILE *dst = fopen(config_file, "w");

if (!src || !dst)
{
printf("[PLUGIN]: Failed to copy default config\n");
if (src) fclose(src);
if (dst) fclose(dst);
if (src)
fclose(src);
if (dst)
fclose(dst);
return -1;
}

char buffer[1024];
size_t bytes;
while ((bytes = fread(buffer, 1, sizeof(buffer), src)) > 0)
{
fwrite(buffer, 1, bytes, dst);
}

fclose(src);
fclose(dst);
printf("[PLUGIN]: Successfully copied default config to %s\n", config_file);
Expand All @@ -146,11 +169,12 @@ int plugin_driver_load_config(plugin_driver_t *driver, const char *config_file)
}

driver->plugin_count = config_count;
has_python_plugin = 0;
has_python_plugin = 0;
for (int w = 0; w < config_count; w++)
{
memcpy(&driver->plugins[w].config, &configs[w], sizeof(plugin_config_t));
if (configs[w].type == PLUGIN_TYPE_PYTHON) {
if (configs[w].type == PLUGIN_TYPE_PYTHON)
{
has_python_plugin = 1;
}
}
Expand All @@ -170,7 +194,9 @@ int plugin_driver_load_config(plugin_driver_t *driver, const char *config_file)
plugin_manager_destroy(plugin->manager);
return -1;
}
} else if (plugin->config.type == PLUGIN_TYPE_NATIVE) {
}
else if (plugin->config.type == PLUGIN_TYPE_NATIVE)
{
if (native_plugin_get_symbols(plugin) != 0)
{
fprintf(stderr, "Failed to get native plugin symbols for: %s\n",
Expand All @@ -195,14 +221,14 @@ int plugin_driver_init(plugin_driver_t *driver)
for (int i = 0; i < driver->plugin_count; i++)
{
plugin_instance_t *plugin = &driver->plugins[i];

// Skip disabled plugins
if (!plugin->config.enabled)
{
printf("[PLUGIN]: Skipping disabled plugin: %s\n", plugin->config.name);
continue;
}

if (plugin->config.type == PLUGIN_TYPE_PYTHON && plugin->python_plugin &&
plugin->python_plugin->pFuncInit)
{
Expand All @@ -218,7 +244,7 @@ int plugin_driver_init(plugin_driver_t *driver)
// Call the Python init function with proper capsule
PyObject *result =
PyObject_CallFunctionObjArgs(plugin->python_plugin->pFuncInit, args, NULL);

// Store the capsule reference for the lifetime of the plugin
plugin->python_plugin->args_capsule = args;

Expand All @@ -236,7 +262,8 @@ int plugin_driver_init(plugin_driver_t *driver)
{
// Generate structured args for native plugin
plugin_runtime_args_t *args =
(plugin_runtime_args_t *)generate_structured_args_with_driver(PLUGIN_TYPE_NATIVE, driver, i);
(plugin_runtime_args_t *)generate_structured_args_with_driver(PLUGIN_TYPE_NATIVE,
driver, i);
if (!args)
{
fprintf(stderr, "Failed to generate runtime args for native plugin: %s\n",
Expand Down Expand Up @@ -276,23 +303,23 @@ int plugin_driver_start(plugin_driver_t *driver)
return 0;
}


if (has_python_plugin) {
if (has_python_plugin)
{
main_tstate = PyEval_SaveThread();
gstate = PyGILState_Ensure();
}

for (int i = 0; i < driver->plugin_count; i++)
{
plugin_instance_t *plugin = &driver->plugins[i];

// Skip disabled plugins
if (!plugin->config.enabled)
{
printf("[PLUGIN]: Skipping disabled plugin during start: %s\n", plugin->config.name);
continue;
}

switch (plugin->config.type)
{
case PLUGIN_TYPE_PYTHON:
Expand Down Expand Up @@ -347,7 +374,8 @@ int plugin_driver_start(plugin_driver_t *driver)
break;
}
}
if (has_python_plugin) {
if (has_python_plugin)
{
PyGILState_Release(gstate);
}
return 0;
Expand Down Expand Up @@ -475,7 +503,8 @@ void plugin_driver_destroy(plugin_driver_t *driver)
return;
}

if (has_python_plugin) {
if (has_python_plugin)
{
gstate = PyGILState_Ensure();
}

Expand All @@ -499,10 +528,12 @@ void plugin_driver_destroy(plugin_driver_t *driver)
if (plugin->native_plugin->cleanup)
{
plugin->native_plugin->cleanup();
printf("[PLUGIN]: Native plugin %s cleaned up successfully.\n", plugin->config.name);
printf("[PLUGIN]: Native plugin %s cleaned up successfully.\n",
plugin->config.name);
}
// Close the shared library handle
if (plugin->native_plugin->handle) {
if (plugin->native_plugin->handle)
{
dlclose(plugin->native_plugin->handle);
plugin->native_plugin->handle = NULL;
}
Expand All @@ -512,7 +543,8 @@ void plugin_driver_destroy(plugin_driver_t *driver)
}
}

if (has_python_plugin) {
if (has_python_plugin)
{
PyGILState_Release(gstate);
PyEval_RestoreThread(main_tstate);
Py_FinalizeEx();
Expand Down Expand Up @@ -860,28 +892,32 @@ int native_plugin_get_symbols(plugin_instance_t *plugin)
native_bundle->start = (plugin_start_loop_func_t)dlsym(handle, "start_loop");
if (!native_bundle->start)
{
fprintf(stderr, "Warning: 'start_loop' function not found in native plugin '%s' (optional)\n",
fprintf(stderr,
"Warning: 'start_loop' function not found in native plugin '%s' (optional)\n",
plugin->config.path);
}

native_bundle->stop = (plugin_stop_loop_func_t)dlsym(handle, "stop_loop");
if (!native_bundle->stop)
{
fprintf(stderr, "Warning: 'stop_loop' function not found in native plugin '%s' (optional)\n",
fprintf(stderr,
"Warning: 'stop_loop' function not found in native plugin '%s' (optional)\n",
plugin->config.path);
}

native_bundle->cycle_start = (plugin_cycle_start_func_t)dlsym(handle, "cycle_start");
if (!native_bundle->cycle_start)
{
fprintf(stderr, "Warning: 'cycle_start' function not found in native plugin '%s' (optional)\n",
fprintf(stderr,
"Warning: 'cycle_start' function not found in native plugin '%s' (optional)\n",
plugin->config.path);
}

native_bundle->cycle_end = (plugin_cycle_end_func_t)dlsym(handle, "cycle_end");
if (!native_bundle->cycle_end)
{
fprintf(stderr, "Warning: 'cycle_end' function not found in native plugin '%s' (optional)\n",
fprintf(stderr,
"Warning: 'cycle_end' function not found in native plugin '%s' (optional)\n",
plugin->config.path);
}

Expand Down
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