feat: use faster method for nix package count (#57)

* Use fast nix package count from libmacchina

* Update docs on slow nix package count

* Update libmacchina to 7.3.0

Cargo.toml

@@ -21,7 +21,7 @@ globset = "0.4.10"
 dotenvy = "0.15.6"
 glob = "0.3.1"
 which = "4.4.0"
-libmacchina = "7.2.3"
+libmacchina = "7.3.0"
 crossterm = "0.27.0"
 os-release = "0.1.0"
 

README.md

@@ -83,13 +83,9 @@ managers. For more info, see [Improving Performance](#imp_perf)._
 
 ### Improving Performance
 
-The by far slowest part of the `pfetch` execution time is counting the installed
-packages. For most package managers this is still very fast, but there are some
-(currently `nix` (and `zypper`, if `rpm-devel` is not installed)) that take
-~500ms to report installed packages, which takes away all performance benefits
-of the Rust version. If you have one or more of these installed, you can skip
-counting them by setting the `PF_FAST_PKG_COUNT` environment variable to any
-value.
+Counting packages of `zypper` can be sped up a lot by installing the `rpm-devel`
+package. If the `zypper` package count takes too long, it can be disabled by
+setting the `PF_FAST_PKG_COUNT` environment variable to any value.
 
 ## Configuration
 
@@ -172,7 +168,7 @@ USER=""
 # Which hostname to display.
 HOSTNAME=""
 
-# Skip package managers that take "long" to query package count (like nix)
+# Skip zypper package count if only slow method is available
 PF_FAST_PKG_COUNT=1
 ```
 

src/lib.rs

@@ -84,18 +84,17 @@ fn packages(
         | PackageManager::Xbps
         | PackageManager::Apk
         | PackageManager::Portage
+        | PackageManager::Nix
         | PackageManager::Opkg => get_macchina_package_count(
             macchina_package_count,
             &format!("{pkg_manager:?}").to_lowercase(),
         )
         .unwrap_or(0),
-        // macchina only supports sqlite database backend for rpm
         PackageManager::Rpm => match get_macchina_package_count(
             macchina_package_count,
             &format!("{pkg_manager:?}").to_lowercase(),
         ) {
             Some(count) => count,
-            // for other databases run `rpm` (slow), see Macchina-CLI/libmacchina#154
             None => {
                 if !skip_slow {
                     run_and_count_lines("rpm", &["-qa"])
@@ -132,23 +131,6 @@ fn packages(
                 0
             }
         }
-        PackageManager::Nix => {
-            if check_if_command_exists("nix-store") && !skip_slow {
-                run_and_count_lines(
-                    "nix-store",
-                    &["-q", "--requisites", "/run/current-system/sw"],
-                ) + run_and_count_lines(
-                    "nix-store",
-                    &[
-                        "-q",
-                        "--requisites",
-                        &format!("{}/.nix-profile", env::var("HOME").unwrap_or_default()),
-                    ],
-                )
-            } else {
-                0
-            }
-        }
     }
 }