Inline fill_via_try_fill implicit error handling, and revise

Author: dhardy

src/impls.rs

@@ -167,40 +167,4 @@ pub fn next_u64_via_fill<R: Rng+?Sized>(rng: &mut R) -> u64 {
     impl_uint_from_fill!(rng, u64, 8)
 }
 
-/// Implement `fill` via `try_fill` with implicit error handling.
-pub fn fill_via_try_fill<R: Rng+?Sized>(rng: &mut R, dest: &mut [u8]) {
-    const WAIT_DUR_MS: u32 = 100;
-    const MAX_WAIT: u32 = (1 * 60 * 1000) / WAIT_DUR_MS;
-    const TRANSIENT_STEP: u32 = MAX_WAIT / 8;
-    let mut err_count = 0;
-    
-    loop {
-        if let Err(e) = rng.try_fill(dest) {
-            if e.kind().should_retry() {
-                if err_count > MAX_WAIT {
-                    // TODO: log details & cause?
-                    panic!("Too many RNG errors or timeout; last error: {}", e.msg());
-                }
-                
-                if e.kind().should_wait() {
-                    #[cfg(feature="std")]{
-                        let dur = ::std::time::Duration::from_millis(WAIT_DUR_MS as u64);
-                        ::std::thread::sleep(dur);
-                    }
-                    err_count += 1;
-                } else {
-                    err_count += TRANSIENT_STEP;
-                }
-                
-                continue;
-            }
-            
-            // TODO: log details & cause?
-            panic!("Fatal RNG error: {}", e.msg());
-        }
-        
-        break;
-    }
-}
-
 // TODO: implement tests for the above

src/os.rs

@@ -61,7 +61,38 @@ impl Rng for OsRng {
     }
 
     fn fill(&mut self, dest: &mut [u8]) {
-        impls::fill_via_try_fill(self, dest)
+        // We cannot return Err(..), so we try to handle before panicking.
+        const WAIT_DUR_MS: u32 = 100;   // retry every 100ms
+        const MAX_WAIT: u32 = (10 * 1000) / WAIT_DUR_MS;    // max 10s
+        const TRANSIENT_STEP: u32 = MAX_WAIT / 8;
+        let mut err_count = 0;
+        
+        loop {
+            if let Err(e) = self.try_fill(dest) {
+                // TODO: add logging to explain why we wait and the full cause
+                if e.kind().should_retry() {
+                    if err_count > MAX_WAIT {
+                        panic!("Too many RNG errors or timeout; last error: {}", e.msg());
+                    }
+                    
+                    if e.kind().should_wait() {
+                        #[cfg(feature="std")]{
+                            let dur = ::std::time::Duration::from_millis(WAIT_DUR_MS as u64);
+                            ::std::thread::sleep(dur);
+                        }
+                        err_count += 1;
+                    } else {
+                        err_count += TRANSIENT_STEP;
+                    }
+                    
+                    continue;
+                }
+                
+                panic!("Fatal RNG error: {}", e.msg());
+            }
+            
+            break;
+        }
     }
 
     fn try_fill(&mut self, v: &mut [u8]) -> Result<(), Error> {