feat: add simple retry for text file busy (#155)

adds a primitive retry logic for text file busy errors

by checking if the file now exists and has the right checksum, in which
case we can exit early or retry install

Author: mattsse

crates/svm-rs/src/install.rs

@@ -57,7 +57,12 @@ pub fn blocking_install(version: &Version) -> Result<PathBuf, SvmError> {
     // same version of solc.
     let _lock = try_lock_file(lock_path)?;
 
-    do_install(version, &binbytes, artifact.to_string().as_str())
+    do_install_and_retry(
+        version,
+        &binbytes,
+        artifact.to_string().as_str(),
+        &expected_checksum,
+    )
 }
 
 /// Installs the provided version of Solc in the machine.
@@ -98,7 +103,54 @@ pub async fn install(version: &Version) -> Result<PathBuf, SvmError> {
     // same version of solc.
     let _lock = try_lock_file(lock_path)?;
 
-    do_install(version, &binbytes, artifact.to_string().as_str())
+    do_install_and_retry(
+        version,
+        &binbytes,
+        artifact.to_string().as_str(),
+        &expected_checksum,
+    )
+}
+
+/// Same as [`do_install`] but retries "text file busy" errors.
+fn do_install_and_retry(
+    version: &Version,
+    binbytes: &[u8],
+    artifact: &str,
+    expected_checksum: &[u8],
+) -> Result<PathBuf, SvmError> {
+    let mut retries = 0;
+
+    loop {
+        return match do_install(version, binbytes, artifact) {
+            Ok(path) => Ok(path),
+            Err(err) => {
+                // installation failed
+                if retries > 2 {
+                    return Err(err);
+                }
+                retries += 1;
+                // check if this failed due to a text file busy, which indicates that a different process started using the target file
+                if err.to_string().to_lowercase().contains("text file busy") {
+                    // busy solc can be in use for a while (e.g. if compiling a large project), so we check if the file exists and has the correct checksum
+                    let solc_path = version_binary(&version.to_string());
+                    if solc_path.exists() {
+                        if let Ok(content) = fs::read(&solc_path) {
+                            if ensure_checksum(&content, version, expected_checksum).is_ok() {
+                                // checksum of the existing file matches the expected release checksum
+                                return Ok(solc_path);
+                            }
+                        }
+                    }
+
+                    // retry after some time
+                    std::thread::sleep(Duration::from_millis(250));
+                    continue;
+                }
+
+                Err(err)
+            }
+        };
+    }
 }
 
 fn do_install(version: &Version, binbytes: &[u8], _artifact: &str) -> Result<PathBuf, SvmError> {