Add max depth parameter for crawl

src/crawl.rs

@@ -1,28 +1,40 @@
-use anyhow::Error;
-use futures::try_join;
 use crate::federated_instances::GetSiteResponse;
 use crate::node_info::NodeInfo;
+use crate::REQUEST_TIMEOUT;
+use anyhow::Error;
+use futures::try_join;
 use reqwest::Client;
 use serde::Serialize;
 use std::collections::VecDeque;
-use crate::REQUEST_TIMEOUT;
 
-pub async fn crawl(start_instances: Vec<String>) -> Result<Vec<InstanceDetails>, Error> {
-  let mut pending_instances = VecDeque::from(start_instances);
+pub async fn crawl(
+    start_instances: Vec<String>,
+    max_depth: i32,
+) -> Result<Vec<InstanceDetails>, Error> {
+    let mut pending_instances: VecDeque<CrawlInstance> = start_instances
+        .iter()
+        .map(|s| CrawlInstance::new(s.to_string(), 0))
+        .collect();
     let mut crawled_instances = vec![];
     let mut instance_details = vec![];
     while let Some(current_instance) = pending_instances.pop_back() {
-    crawled_instances.push(current_instance.clone());
-    match fetch_instance_details(&current_instance).await {
+        crawled_instances.push(current_instance.domain.clone());
+        if current_instance.depth > max_depth {
+            continue;
+        }
+        match fetch_instance_details(&current_instance.domain).await {
             Ok(details) => {
                 instance_details.push(details.to_owned());
                 for i in details.linked_instances {
-          if !crawled_instances.contains(&i) && !pending_instances.contains(&i) {
-            pending_instances.push_back(i);
+                    let is_in_crawled = crawled_instances.contains(&i);
+                    let is_in_pending = pending_instances.iter().any(|p| p.domain == i);
+                    if !is_in_crawled && !is_in_pending {
+                        let ci = CrawlInstance::new(i, current_instance.depth + 1);
+                        pending_instances.push_back(ci);
                     }
                 }
             }
-      Err(e) => eprintln!("Failed to crawl {}: {}", current_instance, e),
+            Err(e) => eprintln!("Failed to crawl {}: {}", current_instance.domain, e),
         }
     }
 
@@ -46,6 +58,17 @@ pub struct InstanceDetails {
     pub linked_instances: Vec<String>,
 }
 
+struct CrawlInstance {
+  domain: String,
+  depth: i32,
+}
+
+impl CrawlInstance {
+  pub fn new(domain: String, depth: i32) -> CrawlInstance {
+    CrawlInstance { domain, depth }
+  }
+}
+
 async fn fetch_instance_details(domain: &str) -> Result<InstanceDetails, Error> {
     let client = Client::default();
 

src/lib.rs

@@ -1,8 +1,9 @@
 use std::time::Duration;
 
+pub mod crawl;
 pub mod federated_instances;
 pub mod node_info;
-pub mod crawl;
 
 pub const REQUEST_TIMEOUT: Duration = Duration::from_secs(10);
 pub const START_INSTANCES: [&'static str; 1] = ["lemmy.ml"];
+pub const MAX_CRAWL_DEPTH: i32 = 2;

src/main.rs

@@ -1,14 +1,14 @@
 use anyhow::Error;
-use serde::Serialize;
-use lemmy_stats_crawler::START_INSTANCES;
 use lemmy_stats_crawler::crawl::{crawl, InstanceDetails};
+use lemmy_stats_crawler::{MAX_CRAWL_DEPTH, START_INSTANCES};
+use serde::Serialize;
 
 #[tokio::main]
 pub async fn main() -> Result<(), Error> {
     let start_instances = START_INSTANCES.iter().map(|s| s.to_string()).collect();
 
     eprintln!("Crawling...");
-    let instance_details = crawl(start_instances).await?;
+    let instance_details = crawl(start_instances, MAX_CRAWL_DEPTH).await?;
     let total_stats = aggregate(instance_details);
 
     println!("{}", serde_json::to_string(&total_stats)?);