all: Make multithreading support configurable.

This is useful in cases where multi threading is not used.  It is also
currently necessary to turn off threading when compiling with MSVC as
that compiler does not have pthreads.

While here, remove the broken CSNIP_CONF__EMULATE_{READ,WRITE}V
macros from the configuration file; they're not working.

Author: lorinder

CMakeLists.txt

@@ -8,7 +8,16 @@ project(csnip
 # Add module path
 set(CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH} "${CMAKE_SOURCE_DIR}/cmake")
 
-find_package(Threads REQUIRED)
+# Find threading library and enable thread safety if applicable
+find_package(Threads)
+if (Threads_FOUND)
+	set(_dflt_support_threading ON)
+else()
+	set(_dflt_support_threading OFF)
+endif()
+option(SUPPORT_THREADING
+	"Make some modules multithreading safe"
+	${_dflt_support_threading})
 
 include(EnableWarnings)
 include(CxxSetup)

src/csnip/CMakeLists.txt

@@ -1,6 +1,10 @@
 ### Configure csnip
 
-## Step 1: Feature/Environment checks
+## Step 1: User preferences
+
+set(CSNIP_CONF__SUPPORT_THREADING ${SUPPORT_THREADING})
+
+## Step 2: Feature/Environment checks
 
 # Check for various types & APIs in libc and provided
 # libraries.
@@ -166,7 +170,7 @@ set(c_sources
 )
 
 set(csnip_link_libs
-	Threads::Threads
+	$<$<BOOL:${SUPPORT_THREADING}>:Threads::Threads>
 	${LINK_LIBM}
 )
 

src/csnip/csnip_conf.h.in

@@ -20,29 +20,9 @@
  *  will be provided.
  */
 
-/** Use csnip's emulated readv() implementation.
- *
- *  If this option is disabled, csnip will use the system readv()
- *  for the implementation of csnip_x_readv(); if there is no system
- *  readv(), then the function will not be available in this case.
- *
- *  If the option is enabled, csnip's own implementation based on read()
- *  is used.  (That implementation is typically less efficient than the
- *  system one.)
- *
- *  By default this option is disabled if readv() is available, and
- *  enabled if it isn't.
- */
-#cmakedefine CSNIP_CONF__EMULATE_READV
-
-/** Use csnip's emulated writev() implementation.
- *
- *  Anologuous to the similar setting for readv().
- *  @sa CSNIP_CONF__EMULATE_READV
- */
-#cmakedefine CSNIP_CONF__EMULATE_WRITEV
+#cmakedefine CSNIP_CONF__SUPPORT_THREADING
 
-/** @}
+/** @def
  */
 
 /** @defgroup conf_env		Environment properties

src/csnip/log.c

@@ -11,7 +11,9 @@
 #ifdef CSNIP_CONF__HAVE_REGCOMP
 #include <regex.h>
 #endif
+#ifdef CSNIP_CONF__SUPPORT_THREADING
 #include <pthread.h>
+#endif
 
 #define CSNIP_SHORT_NAMES
 #include <csnip/cext.h>
@@ -72,7 +74,9 @@ typedef struct {
 	 *
 	 *  This access lock protects access to ptbl.
 	 */
+#ifdef CSNIP_CONF__SUPPORT_THREADING
 	pthread_rwlock_t lock;
+#endif
 
 	/** Priorities cache */
 	struct priotbl* ptbl;
@@ -109,7 +113,9 @@ static void proc_init(csnip_log_processor* P)
 	P->rules_head = P->rules_tail = NULL;
 	P->min_prio = 100;
 	int err = 0;
+#ifdef CSNIP_CONF__SUPPORT_THREADING
 	pthread_rwlock_init(&P->lock, NULL);
+#endif
 	P->ptbl = ptbl_make(&err); // error handling
 	for (int i = 0; i < Static_len(P->logfmt); ++i)
 		P->logfmt[i] = NULL;
@@ -134,7 +140,9 @@ static void proc_free(csnip_log_processor* P)
 	}
 
 	/* Free lock */
+#ifdef CSNIP_CONF__SUPPORT_THREADING
 	pthread_rwlock_destroy(&P->lock);
+#endif
 
 	/* Free the hashing table */
 	ptbl_free(P->ptbl);
@@ -419,9 +427,13 @@ void csnip_log__print(
 	csnip_log_processor* P = proc;
 
 	/* Check whether to display */
+#ifdef CSNIP_CONF__SUPPORT_THREADING
 	pthread_rwlock_rdlock(&P->lock);
+#endif
 	comp_prio* cp = ptbl_find(proc->ptbl, component);
+#ifdef CSNIP_CONF__SUPPORT_THREADING
 	pthread_rwlock_unlock(&P->lock);
+#endif
 	if (cp != NULL) {
 		if (prio < cp->min_prio)
 			return;
@@ -451,9 +463,13 @@ void csnip_log__print(
 			.component = component,
 			.min_prio = comp_min_prio
 		};
+#ifdef CSNIP_CONF__SUPPORT_THREADING
 		pthread_rwlock_wrlock(&P->lock);
+#endif
 		ptbl_insert(P->ptbl, NULL, Pent);
+#ifdef CSNIP_CONF__SUPPORT_THREADING
 		pthread_rwlock_unlock(&P->lock);
+#endif
 
 		/* Check if we should display */
 		if (prio < Pent.min_prio)