Factored out the common current_time function.

Also expanded the comments on `get_cache_dir_for`.

Closes #1.

src/platform.rs

@@ -4,9 +4,35 @@ This module is for platform-specific stuff.
 
 pub use self::inner::{current_time, file_last_modified, get_cache_dir_for};
 
+#[cfg(any(unix, windows))]
+mod inner_unix_or_windows {
+    extern crate time;
+
+    /**
+    Gets the current system time, in milliseconds since the UNIX epoch.
+    */
+    pub fn current_time() -> u64 {
+        /*
+        This is kinda dicey, since *ideally* both this function and `file_last_modified` would be using the same underlying APIs.  They are not, insofar as I know.
+
+        At least, not when targetting Windows.
+
+        That said, so long as everything is in the same units and uses the same epoch, it should be fine.
+        */
+        let now_1970_utc = time::now_utc().to_timespec();
+        if now_1970_utc.sec < 0 || now_1970_utc.nsec < 0 {
+            // Fuck it.
+            return 0
+        }
+        let now_ms_1970_utc = (now_1970_utc.sec as u64 * 1000)
+            + (now_1970_utc.nsec as u64 / 1_000_000);
+        now_ms_1970_utc
+    }
+}
+
 #[cfg(unix)]
 mod inner {
-    extern crate time;
+    pub use super::inner_unix_or_windows::current_time;
 
     use std::path::{Path, PathBuf};
     use std::{cmp, env, fs};
@@ -26,22 +52,10 @@ mod inner {
     }
 
     /**
-    Gets the current system time, in milliseconds since the UNIX epoch.
-    */
-    pub fn current_time() -> u64 {
-        /*
-        This is kinda dicey, since *ideally* both this function and `file_last_modified` would be using the same underlying APIs.  They are not, insofar as I know.
-        */
-        let now_1970_utc = time::now_utc().to_timespec();
-        if now_1970_utc.sec < 0 || now_1970_utc.nsec < 0 {
-            // Fuck it.
-            return 0
-        }
-        let now_ms_1970_utc = (now_1970_utc.sec as u64 * 1000)
-            + (now_1970_utc.nsec as u64 / 1_000_000);
-        now_ms_1970_utc
-    }
+    Get a directory suitable for storing user- and machine-specific data which may or may not be persisted across sessions.
 
+    This is chosen to match the location where Cargo places its cache data.
+    */
     pub fn get_cache_dir_for<P>(product: P) -> Result<PathBuf, MainError>
     where P: AsRef<Path> {
         let home = match env::var_os("HOME") {
@@ -68,6 +82,8 @@ pub mod inner {
     extern crate winapi;
     extern crate uuid;
 
+    pub use super::inner_unix_or_windows::current_time;
+
     use std::ffi::OsString;
     use std::fmt;
     use std::fs;
@@ -95,28 +111,11 @@ pub mod inner {
         mtime_ms_1970_utc
     }
 
-    /**
-    Gets the current system time, in milliseconds since the UNIX epoch.
-    */
-    pub fn current_time() -> u64 {
-        extern crate time;
-
-        /*
-        This is kinda dicey, since *ideally* both this function and `file_last_modified` would be using the same underlying APIs.  They are not, insofar as I know.
-        */
-        let mut now_1970_utc = time::now_utc().to_timespec();
-        if now_1970_utc.sec < 0 || now_1970_utc.nsec < 0 {
-            // Fuck it.
-            now_1970_utc = time::Timespec::new(0, 0);
-        }
-        let now_ms_1970_utc = (now_1970_utc.sec as u64 * 1000)
-            + (now_1970_utc.nsec as u64 / 1_000_000);
-        now_ms_1970_utc
-    }
-
     /**
     Get a directory suitable for storing user- and machine-specific data which may or may not be persisted across sessions.
 
+    This is *not* chosen to match the location where Cargo places its cache data, because Cargo is *wrong*.  This is at least *less wrong*.
+
     On Windows, LocalAppData is where user- and machine- specific data should go, but it *might* be more appropriate to use whatever the official name for "Program Data" is, though.
     */
     pub fn get_cache_dir_for<P>(product: P) -> Result<PathBuf, MainError>