Fixed PDFium initialization logic (#771)

runtime/src/pdfium.rs

@@ -1,19 +1,36 @@
+use std::error::Error;
 use std::sync::Mutex;
 use once_cell::sync::Lazy;
 use pdfium_render::prelude::Pdfium;
 use log::{error, warn};
 
 pub static PDFIUM_LIB_PATH: Lazy<Mutex<Option<String>>> = Lazy::new(|| Mutex::new(None));
+static PDFIUM: Lazy<Mutex<Option<Pdfium>>> = Lazy::new(|| Mutex::new(None));
 
 pub trait PdfiumInit {
-    fn ai_studio_init() -> Result<Pdfium, Box<dyn std::error::Error + Send + Sync>>;
+    fn ai_studio_init() -> Result<Pdfium, Box<dyn Error + Send + Sync>>;
 }
 
 impl PdfiumInit for Pdfium {
 
     /// Initializes the PDFium library for AI Studio.
-    fn ai_studio_init() -> Result<Pdfium, Box<dyn std::error::Error + Send + Sync>> {
+    fn ai_studio_init() -> Result<Pdfium, Box<dyn Error + Send + Sync>> {
-        let lib_path = PDFIUM_LIB_PATH.lock().unwrap();
+        let mut pdfium = PDFIUM.lock().unwrap();
+        if let Some(pdfium) = pdfium.as_ref() {
+            return Ok(pdfium.clone());
+        }
+
+        let loaded_pdfium = load_pdfium().map_err(|error| {
+            Box::new(std::io::Error::other(error)) as Box<dyn Error + Send + Sync>
+        })?;
+        *pdfium = Some(loaded_pdfium.clone());
+
+        Ok(loaded_pdfium)
+    }
+}
+
+fn load_pdfium() -> Result<Pdfium, String> {
+    let lib_path = PDFIUM_LIB_PATH.lock().unwrap().clone();
     if let Some(path) = lib_path.as_ref() {
         return match Pdfium::bind_to_library(Pdfium::pdfium_platform_library_name_at_path(path)) {
             Ok(binding) => Ok(Pdfium::new(binding)),
@@ -21,11 +38,12 @@ impl PdfiumInit for Pdfium {
                 match Pdfium::bind_to_system_library() {
                     Ok(binding) => Ok(Pdfium::new(binding)),
                     Err(system_error) => {
-                            error!(
+                        let error_message = format!(
                             "Failed to load PDFium from '{path}' and the system library. Developer action (from repo root): run the build script once to download the required PDFium version: `cd app/Build` and `dotnet run build`. Details: library error: '{library_error}'; system error: '{system_error}'."
                         );
 
-                            Err(Box::new(system_error))
+                        error!("{error_message}");
+                        Err(error_message)
                     }
                 }
             }
@@ -36,12 +54,12 @@ impl PdfiumInit for Pdfium {
     match Pdfium::bind_to_system_library() {
         Ok(binding) => Ok(Pdfium::new(binding)),
         Err(system_error) => {
-                error!(
+            let error_message = format!(
                 "Failed to load PDFium from the system library. Developer action (from repo root): run the build script once to download the required PDFium version: `cd app/Build` and `dotnet run build`. Details: '{system_error}'."
             );
 
-                Err(Box::new(system_error))
+            error!("{error_message}");
-            }
+            Err(error_message)
         }
     }
 }