fix: optimize string reading in LabVIEW by returning string length fr…

…om rust - previously, the string reading was one byte at a time in a loop until null character (\00) - now, the shared library functions return the string length and LabVIEW reads the entire string from memory in one shot - result is that string reading (and general performance of the library) is significantly faster refs: #12
JKISoftware · Nov 15, 2023 · 11e9414 · 11e9414
1 parent d7d7d24
commit 11e9414
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Showing 19 changed files with 95 additions and 10 deletions.
diff --git a/lv_src/Doc/check_for_parse_errors.vi b/lv_src/Doc/check_for_parse_errors.vi
diff --git a/lv_src/Doc/get_table.vi b/lv_src/Doc/get_table.vi
diff --git a/lv_src/Doc/list_tables.vi b/lv_src/Doc/list_tables.vi
diff --git a/lv_src/Doc/to_toml_string.vi b/lv_src/Doc/to_toml_string.vi
diff --git a/lv_src/InlineTable/list_items.vi b/lv_src/InlineTable/list_items.vi
diff --git a/lv_src/Item/get_item_type.vi b/lv_src/Item/get_item_type.vi
diff --git a/lv_src/Table/list_items.vi b/lv_src/Table/list_items.vi
diff --git a/lv_src/Table/to_string.vi b/lv_src/Table/to_string.vi
diff --git a/lv_src/Value/get_value_for_string.vi b/lv_src/Value/get_value_for_string.vi
diff --git a/lv_src/Value/get_value_type.vi b/lv_src/Value/get_value_type.vi
diff --git a/lv_src/dragon_toml_32.dll b/lv_src/dragon_toml_32.dll
diff --git a/lv_src/dragon_toml_64.dll b/lv_src/dragon_toml_64.dll
diff --git a/lv_src/dragon_toml_64.so b/lv_src/dragon_toml_64.so
diff --git a/lv_src/support/read_c_string_at_memory_address.vi b/lv_src/support/read_c_string_at_memory_address.vi
diff --git a/lv_src/support/support.read_and_free_array_multiline_string_at_address.vi b/lv_src/support/support.read_and_free_array_multiline_string_at_address.vi
diff --git a/lv_src/support/support.read_and_free_string_at_address.vi b/lv_src/support/support.read_and_free_string_at_address.vi
diff --git a/lv_src/toml/open.vi b/lv_src/toml/open.vi
diff --git a/lv_src/toml/write_subtable_key_string.vi b/lv_src/toml/write_subtable_key_string.vi
diff --git a/src/lib.rs b/src/lib.rs
@@ -9,9 +9,18 @@ use toml_edit::{Document, InlineTable, Item, Table, Value};
 // return any TOML parse error as a string using toml_edit::TomlError
 #[allow(dead_code)]
 #[no_mangle]
-pub extern "C" fn toml_edit_doc_get_error(toml_str: *const c_char) -> *mut c_char {
+pub extern "C" fn toml_edit_doc_get_error(
+    toml_str: *const c_char,
+    num_bytes: *mut u32,
+) -> *mut c_char {
     let toml_str = unsafe { CStr::from_ptr(toml_str).to_string_lossy().into_owned() };
 
+    // pass the length of the string back to the caller through the num_bytes pointer
+    let return_value_length = toml_str.len() as u32;
+    unsafe {
+        *num_bytes = return_value_length;
+    }
+
     // try to parse the TOML string
     return match Document::from_str(&toml_str) {
         Ok(_) => {
@@ -48,7 +57,10 @@ pub extern "C" fn toml_edit_doc_from_string(toml_str: *const c_char) -> *mut c_v
 // return a toml string from a Document
 #[allow(dead_code)]
 #[no_mangle]
-pub extern "C" fn toml_edit_doc_to_string(doc: *mut c_void) -> *mut c_char {
+pub extern "C" fn toml_edit_doc_to_string(
+    doc: *mut c_void,
+    num_bytes: *mut u32,
+) -> *mut c_char {
     // todo: add better error return
     if doc.is_null() {
         println!("Document pointer is null");
@@ -60,6 +72,15 @@ pub extern "C" fn toml_edit_doc_to_string(doc: *mut c_void) -> *mut c_char {
         toml_str => toml_str,
     };
 
+
+    // pass the length of the string back to the caller through the num_bytes pointer
+
+    let return_value_length = toml_str.len() as u32;
+    unsafe {
+        *num_bytes = return_value_length;
+    }
+
+
     let raw_string = match CString::new(toml_str).unwrap().into_raw() {
         ptr if ptr.is_null() => {
             println!("Unable to allocate memory for string");
@@ -105,7 +126,10 @@ pub extern "C" fn toml_edit_doc_close(doc: *mut c_void) {
 // convert from a Table to a toml string
 #[allow(dead_code)]
 #[no_mangle]
-pub extern "C" fn toml_edit_table_to_string(table: *mut c_void) -> *mut c_char {
+pub extern "C" fn toml_edit_table_to_string(
+    table: *mut c_void,
+    num_bytes: *mut u32,
+) -> *mut c_char {
     if table.is_null() {
         println!("Table pointer is null");
         return CString::new("").unwrap().into_raw();
@@ -116,6 +140,12 @@ pub extern "C" fn toml_edit_table_to_string(table: *mut c_void) -> *mut c_char {
         toml_str => toml_str,
     };
 
+    // pass the length of the string back to the caller through the num_bytes pointer
+    let return_value_length = toml_str.len() as u32;
+    unsafe {
+        *num_bytes = return_value_length;
+    }
+
     let raw_string = match CString::new(toml_str).unwrap().into_raw() {
         ptr if ptr.is_null() => {
             println!("Unable to allocate memory for string");
@@ -169,7 +199,10 @@ pub extern "C" fn toml_edit_inline_table_to_item(inline_table: *mut c_void) -> *
 // list the tables in a Document as a multi-line string
 #[allow(dead_code)]
 #[no_mangle]
-pub extern "C" fn toml_edit_doc_list_tables(doc: *mut c_void) -> *mut c_char {
+pub extern "C" fn toml_edit_doc_list_tables(
+    doc: *mut c_void,
+    num_bytes: *mut u32,
+) -> *mut c_char {
     if doc.is_null() {
         println!("Document pointer is null");
         return CString::new("").unwrap().into_raw();
@@ -183,6 +216,13 @@ pub extern "C" fn toml_edit_doc_list_tables(doc: *mut c_void) -> *mut c_char {
         table_list.push_str(&format!("{}\n", table.0));
     }
 
+    // pass the length of the string back to the caller through the num_bytes pointer
+
+    let return_value_length = table_list.len() as u32;
+    unsafe {
+        *num_bytes = return_value_length;
+    }
+
     let raw_string = match CString::new(table_list).unwrap().into_raw() {
         ptr if ptr.is_null() => {
             println!("Unable to allocate memory for string");
@@ -363,7 +403,10 @@ pub extern "C" fn toml_edit_table_set_item(
 // takes a value as input
 #[allow(dead_code)]
 #[no_mangle]
-pub extern "C" fn toml_edit_get_value_type(value: *mut c_void) -> *mut c_char {
+pub extern "C" fn toml_edit_get_value_type(
+    value: *mut c_void,
+    num_bytes: *mut u32,
+) -> *mut c_char {
     if value.is_null() {
         println!("Value is null");
         return CString::new("None").unwrap().into_raw();
@@ -381,6 +424,12 @@ pub extern "C" fn toml_edit_get_value_type(value: *mut c_void) -> *mut c_char {
         Value::InlineTable(_) => "InlineTable",
     };
 
+    // pass the length of the string back to the caller through the num_bytes pointer
+    let return_value_length = value_type.len() as u32;
+    unsafe {
+        *num_bytes = return_value_length;
+    }
+
     let raw_string = match CString::new(value_type).unwrap().into_raw() {
         ptr if ptr.is_null() => {
             println!("Unable to allocate memory for string");
@@ -396,7 +445,10 @@ pub extern "C" fn toml_edit_get_value_type(value: *mut c_void) -> *mut c_char {
 // takes a Item as input
 #[allow(dead_code)]
 #[no_mangle]
-pub extern "C" fn toml_edit_item_get_type(item: *mut c_void) -> *mut c_char {
+pub extern "C" fn toml_edit_item_get_type(
+    item: *mut c_void,
+    num_bytes: *mut u32,
+) -> *mut c_char {
     // check if item has a null value
     if item.is_null() {
         let raw_string = match CString::new("None").unwrap().into_raw() {
@@ -419,6 +471,12 @@ pub extern "C" fn toml_edit_item_get_type(item: *mut c_void) -> *mut c_char {
         Item::Table(_) => "Table",
     };
 
+    // pass the length of the string back to the caller through the num_bytes pointer
+    let return_value_length = item_type.len() as u32;
+    unsafe {
+        *num_bytes = return_value_length;
+    }
+
     let raw_string = match CString::new(item_type).unwrap().into_raw() {
         ptr if ptr.is_null() => {
             println!("Unable to allocate memory for string");
@@ -481,10 +539,17 @@ pub extern "C" fn toml_edit_item_into_table(item: *mut c_void) -> *mut c_void {
 }
 
 // get a String typed Value from a value
-// takes a value as input
+// inputs:
+//  - a `value` pointer to a Value
+//  - a `num_bytes` pointer to a u32 that this function will set to the number of bytes in the string
+// returns:
+//  - a pointer to a c_char that is the string
 #[allow(dead_code)]
 #[no_mangle]
-pub extern "C" fn toml_edit_value_get_string(value: *mut c_void) -> *mut c_char {
+pub extern "C" fn toml_edit_value_get_string(
+    value: *mut c_void,
+    num_bytes: *mut u32,
+) -> *mut c_char {
     // need a better error return
     if value.is_null() {
         println!("Value is null");
@@ -501,8 +566,19 @@ pub extern "C" fn toml_edit_value_get_string(value: *mut c_void) -> *mut c_char
         }
     };
 
+
+    // now let's prepare a return string for the caller
+
     let return_value = value.clone().into_value();
 
+
+    // pass the length of the string back to the caller through the num_bytes pointer
+
+    let return_value_length = return_value.len() as u32;
+    unsafe {
+        *num_bytes = return_value_length;
+    }
+
     let raw_string = match CString::new(return_value).unwrap().into_raw() {
         ptr if ptr.is_null() => {
             println!("Unable to allocate memory for string");
@@ -732,7 +808,10 @@ pub extern "C" fn toml_edit_inline_table_contains_item(
 // takes a InlineTable as input
 #[allow(dead_code)]
 #[no_mangle]
-pub extern "C" fn toml_edit_inline_table_list_items(inline_table: *mut c_void) -> *mut c_char {
+pub extern "C" fn toml_edit_inline_table_list_items(
+    inline_table: *mut c_void,
+    num_bytes: *mut u32,
+) -> *mut c_char {
     if inline_table.is_null() {
         println!("InlineTable is null");
         return CString::new("").unwrap().into_raw();
@@ -747,6 +826,12 @@ pub extern "C" fn toml_edit_inline_table_list_items(inline_table: *mut c_void) -
         return_string.push_str("\n");
     }
 
+    // pass the length of the string back to the caller through the num_bytes pointer
+    let return_value_length = return_string.len() as u32;
+    unsafe {
+        *num_bytes = return_value_length;
+    }
+
     let raw_string = match CString::new(return_string).unwrap().into_raw() {
         ptr if ptr.is_null() => {
             println!("Unable to allocate memory for string");
@@ -885,7 +970,7 @@ pub extern "C" fn cstring_free_memory(s: *mut c_char) {
     if s.is_null() {
         return;
     }
-    unsafe { CString::from_raw(s) };
+    unsafe { let _ = CString::from_raw(s); };
 }
 
 #[cfg(test)]