perf(tsort): avoid reading the whole input into memory and intern strings

Author: anastygnome

Cargo.lock

@@ -1,7 +1,7 @@
 # coreutils (uutils)
 # * see the repository LICENSE, README, and CONTRIBUTING files for more information
 
-# spell-checker:ignore (libs) bigdecimal datetime serde bincode gethostid kqueue libselinux mangen memmap uuhelp startswith constness expl unnested logind cfgs
+# spell-checker:ignore (libs) bigdecimal datetime serde bincode gethostid kqueue libselinux mangen memmap uuhelp startswith constness expl unnested logind cfgs interner
 
 [package]
 name = "coreutils"
@@ -403,7 +403,7 @@ uucore_procs = { version = "0.5.0", package = "uucore_procs", path = "src/uucore
 uu_ls = { version = "0.5.0", path = "src/uu/ls" }
 uu_base32 = { version = "0.5.0", path = "src/uu/base32" }
 uutests = { version = "0.5.0", package = "uutests", path = "tests/uutests" }
-
+string-interner = "0.19.0"
 [dependencies]
 clap.workspace = true
 clap_complete = { workspace = true, optional = true }
@@ -414,7 +414,7 @@ selinux = { workspace = true, optional = true }
 textwrap.workspace = true
 uucore.workspace = true
 zip = { workspace = true, optional = true }
-
+string-interner.workspace = true
 
 # * uutils
 uu_test = { optional = true, version = "0.5.0", package = "uu_test", path = "src/uu/test" }
@@ -521,6 +521,7 @@ who = { optional = true, version = "0.5.0", package = "uu_who", path = "src/uu/w
 whoami = { optional = true, version = "0.5.0", package = "uu_whoami", path = "src/uu/whoami" }
 yes = { optional = true, version = "0.5.0", package = "uu_yes", path = "src/uu/yes" }
 
+
 # this breaks clippy linting with: "tests/by-util/test_factor_benches.rs: No such file or directory (os error 2)"
 # factor_benches = { optional = true, version = "0.0.0", package = "uu_factor_benches", path = "tests/benches/factor" }
 

Cargo.toml

@@ -1,3 +1,4 @@
+#spell-checker:ignore (libs) interner
 [package]
 name = "uu_tsort"
 description = "tsort ~ (uutils) topologically sort input (partially ordered) pairs"
@@ -22,7 +23,8 @@ clap = { workspace = true }
 thiserror = { workspace = true }
 uucore = { workspace = true }
 fluent = { workspace = true }
-
+string-interner = { workspace = true }
+nix = { workspace = true, features = ["fs"] } 
 [[bin]]
 name = "tsort"
 path = "src/main.rs"