Add option to disable database concurrency

src/args.rs

@@ -33,6 +33,9 @@ pub struct Args {
     #[clap(long = "skip-cache")]
     /// Do not read from disk cache for Debian database results
     pub skip_cache: bool,
+    #[clap(long = "concurrency", short = 'j', default_value = "24")]
+    /// How many database connections to use concurrently
+    pub concurrency: usize,
     #[clap(long = "no-dev-dependencies")]
     /// Skip dev dependencies.
     pub no_dev_dependencies: bool,

src/debian.rs

@@ -9,8 +9,6 @@ use semver::Version;
 use std::path::PathBuf;
 use std::thread;
 
-const QUERY_THREADS: usize = 24;
-
 #[derive(Debug, Clone)]
 pub struct Pkg {
     pub id: PackageId,
@@ -160,7 +158,7 @@ pub fn populate(graph: &mut Graph, args: &Args) -> Result<(), Error> {
     let (return_tx, return_rx) = crossbeam_channel::unbounded();
 
     info!("Creating thread-pool");
-    for _ in 0..QUERY_THREADS {
+    for _ in 0..args.concurrency {
         let args = args.clone();
         let task_rx = task_rx.clone();
         let return_tx = return_tx.clone();