feat: add memory usage module (#403)

Adds a module to display system memory and swap usage.

4 files changed, 91 insertions, 0 deletions

diff --git a/src/module.rs b/src/module.rs
index 7ebfa53e2..65e69c36d 100644
--- a/src/module.rs
+++ b/src/module.rs
@@ -21,6 +21,7 @@ pub const ALL_MODULES: &[&str] = &[
     "java",
     "jobs",
     "line_break",
+    "memory_usage",
     "nix_shell",
     "nodejs",
     "package",
diff --git a/src/modules/memory_usage.rs b/src/modules/memory_usage.rs
new file mode 100644
index 000000000..b8fe4fbf9
--- /dev/null
+++ b/src/modules/memory_usage.rs
@@ -0,0 +1,87 @@
+use ansi_term::Color;
+
+use super::{Context, Module};
+use byte_unit::{Byte, ByteUnit};
+use sysinfo::{RefreshKind, SystemExt};
+
+/// Creates a module with system memory usage information
+pub fn module<'a>(context: &'a Context) -> Option<Module<'a>> {
+    const DEFAULT_THRESHOLD: i64 = 75;
+    const DEFAULT_SHOW_PERCENTAGE: bool = false;
+    const RAM_CHAR: &str = "🐏 ";
+
+    let mut module = context.new_module("memory_usage");
+
+    let module_style = module
+        .config_value_style("style")
+        .unwrap_or_else(|| Color::White.bold().dimmed());
+
+    let system = sysinfo::System::new_with_specifics(RefreshKind::new().with_system());
+
+    let used_memory_kib = system.get_used_memory();
+    let total_memory_kib = system.get_total_memory();
+    let used_swap_kib = system.get_used_swap();
+    let total_swap_kib = system.get_total_swap();
+
+    let percent_mem_used = (used_memory_kib as f64 / total_memory_kib as f64) * 100.;
+    let percent_swap_used = (used_swap_kib as f64 / total_swap_kib as f64) * 100.;
+
+    let threshold = module
+        .config_value_i64("threshold")
+        .unwrap_or(DEFAULT_THRESHOLD);
+
+    if percent_mem_used.round() < threshold as f64 {
+        return None;
+    }
+
+    let show_percentage = module
+        .config_value_bool("show_percentage")
+        .unwrap_or(DEFAULT_SHOW_PERCENTAGE);
+
+    let (display_mem, display_swap) = if show_percentage {
+        (
+            format!("{:.0}%", percent_mem_used),
+            format!("{:.0}%", percent_swap_used),
+        )
+    } else {
+        fn format_kib(n_kib: u64) -> String {
+            let byte = Byte::from_unit(n_kib as f64, ByteUnit::KiB)
+                .unwrap_or_else(|_| Byte::from_bytes(0));
+            let mut display_bytes = byte.get_appropriate_unit(true).format(0);
+            display_bytes.retain(|c| c != ' ');
+            display_bytes
+        }
+        (
+            format!(
+                "{}/{}",
+                format_kib(used_memory_kib),
+                format_kib(total_memory_kib)
+            ),
+            format!(
+                "{}/{}",
+                format_kib(used_swap_kib),
+                format_kib(total_swap_kib)
+            ),
+        )
+    };
+
+    let show_swap = module
+        .config_value_bool("show_swap")
+        .unwrap_or(total_swap_kib != 0);
+
+    module.new_segment("symbol", RAM_CHAR);
+
+    module.set_style(module_style);
+    if show_swap {
+        module.new_segment(
+            "memory_usage",
+            &format!("{} | {}", display_mem, display_swap),
+        );
+    } else {
+        module.new_segment("memory_usage", &display_mem);
+    }
+
+    module.get_prefix().set_value("");
+
+    Some(module)
+}
diff --git a/src/modules/mod.rs b/src/modules/mod.rs
index 82d3614a7..f073c5a6c 100644
--- a/src/modules/mod.rs
+++ b/src/modules/mod.rs
@@ -12,6 +12,7 @@ mod hostname;
 mod java;
 mod jobs;
 mod line_break;
+mod memory_usage;
 mod nix_shell;
 mod nodejs;
 mod package;
@@ -52,6 +53,7 @@ pub fn handle<'a>(module: &str, context: &'a Context) -> Option<Module<'a>> {
         "nix_shell" => nix_shell::module(context),
         "hostname" => hostname::module(context),
         "time" => time::module(context),
+        "memory_usage" => memory_usage::module(context),
 
         _ => {
             eprintln!("Error: Unknown module {}. Use starship module --list to list out all supported modules.", module);
diff --git a/src/print.rs b/src/print.rs
index 18fe5ea14..eed2ee8b3 100644
--- a/src/print.rs
+++ b/src/print.rs
@@ -26,6 +26,7 @@ const DEFAULT_PROMPT_ORDER: &[&str] = &[
     "golang",
     "java",
     "nix_shell",
+    "memory_usage",
     "aws",
     "env_var",
     "cmd_duration",