Improve fuzzing performance by using arbitrary_len to pick nb_samples

Author: michielp1807

fuzz/fuzz_targets/dictionary_round_trip.rs

@@ -76,10 +76,10 @@ impl arbitrary::Arbitrary<'_> for ArbitraryRoundTrip {
     }
 }
 
-fuzz_target!(|data: (ArbitrarySamples, ArbitraryRoundTrip)| {
+fuzz_target!(|data: (ArbitraryRoundTrip, ArbitrarySamples)| {
     use libzstd_rs_sys::*;
 
-    let (samples, data) = data;
+    let (data, samples) = data;
 
     let src = samples.src;
 

fuzz/src/lib.rs

@@ -17,7 +17,8 @@ impl arbitrary::Arbitrary<'_> for ArbitrarySamples {
 
         let dict_size = max(src.len() / 8, 1024);
         let total_sample_size = dict_size * 11;
-        let nb_samples = u.int_in_range(1..=100)?;
+        // pick number of samples based on remaining randomness that is left
+        let nb_samples = u.arbitrary_len::<usize>()?;
 
         // generate random samples from src
         let mut samples = Vec::with_capacity(total_sample_size);