quick_search/Cargo.toml

[workspace]
resolver = "2"
members = [
    "crates/quicksearch-core",
    "crates/quicksearch-gui",
]

[workspace.package]
version = "1.1.0"
edition = "2021"
license = "GPL-3.0-or-later"
authors = ["Jeremy <jeremy@karsttech.com>"]
repository = "https://code.karsttech.com/jeremy/quick_search.git"

# Fat LTO, one codegen unit. This reverses an earlier decision, so both
# measurements are kept: the old one was right about what it measured, and it
# measured the wrong axis on the wrong kind of build.
#
# WHAT WAS MEASURED BEFORE, against an *incremental* rebuild of the GUI after
# touching core (10.2 s at the defaults):
#
#   lto=thin           67 s   search cold 29.9 ms  warm best 14.77 ms  index cold 459 ms
#   lto=thin,cgu=1    152 s   (build cost alone ruled it out)
#   lto=fat,cgu=1     200 s   search cold 29.2 ms  warm best 14.57 ms  index cold 479 ms
#   (defaults)         10 s   search cold 30.0 ms  warm best 14.92 ms  index cold 478 ms
#
# It concluded that the runtime gain was at the noise floor against a 6.6-19.5x
# longer build. Two things were wrong with that as a decision:
#
#   * It never weighed SIZE, which turns out to be where the effect is.
#   * A 10 s incremental rebuild is the worst possible denominator for a
#     link-time optimization, because the LTO link is nearly the whole cost and
#     there is no compile phase to amortize it against. CI never builds that
#     way; it builds clean.
#
# RE-MEASURED CLEAN, on 6 cores, stripped `target/*/quicksearch`:
#
#                     stripped     vs def   search cold  warm best  index cold
#   (defaults)      28,248,272          -      28.2 ms    14.7 ms     445 ms
#   cgu=1           25,909,616      -8.3%      28.6 ms    14.8 ms     452 ms
#   lto=thin        28,233,296      -0.1%      (not run: no size effect)
#   lto=thin,cgu=1  25,991,536      -8.0%      (not run: worse than cgu=1 alone)
#   lto=fat,cgu=1   24,284,912     -14.0%      27.3 ms    14.1 ms     443 ms
#
# Search is best of three runs; the spreads overlap, so read fat as "3-4%
# faster or even", never as a regression. It is both the fastest and by far the
# smallest, which is why it wins outright.
#
# Two surprises worth keeping. `codegen-units = 1` ALONE is worth 2.3 MB - the
# old table never isolated it, because every cgu=1 row there also carried LTO.
# And `lto = "thin"` alone is worth nothing at all (0.1%), while thin+cgu=1 is
# slightly *worse* than cgu=1 by itself. Thin is not a cheaper fat here; it is
# a different, useless thing.
#
# BUILD COST, clean, 6 cores. The second column is what CI actually pays on top
# of the binaries, since `cargo test --release --workspace` links every test,
# example and bin target - `--release` is `--profile=release`, so this profile
# is theirs too:
#
#                      bins    + all test targets     total
#   (defaults)         143 s          28 s            171 s
#   cgu=1              158 s          41 s            199 s
#   lto=fat,cgu=1      198 s         100 s            298 s
#
# So +127 s on a clean CI run, not the tens of minutes the incremental figure
# above implies. Test targets link cheaply because they are small; it is the
# 320-crate dependency compile that dominates, and cgu=1 spreads across cores.
#
# WHAT IS DELIBERATELY NOT SET:
#
# `strip` would save nothing shipped. The packaging scripts and ci.yml strip the
# staged *copy*, which keeps `target/release/` symbolised for `perf` and for the
# RUST_BACKTRACE=1 release-test backtraces CI prints, and keeps `--no-strip` on
# build-deb.sh and build-appimage.sh meaning something. Setting it here would
# move the same 6.5 MB saving to a place where it costs debuggability.
#
# `panic = "abort"` is the largest win left - it would delete `.gcc_except_table`
# (428 KB after LTO) and most of `.eh_frame` (1.33 MB) - and is unavailable for
# two independent reasons. `extract/pdf.rs` runs `pdf-extract` inside
# `catch_unwind`, so aborting would turn a malformed PDF into a killed process
# instead of one skipped file. And cargo forces every dependency to rebuild with
# unwind when building tests under an abort profile, so `cargo test --release`
# would compile the whole graph a second time.
#
# Non-PIE would remove most of `.rela.dyn` (1.37 MB) and is rejected on
# hardening grounds: this program parses arbitrary user PDFs with a crate known
# to panic on malformed input, which is the last place to give up ASLR.
#
# The vendored OpenSSL (~1.3 MB of `.text`, via SQLCipher) is unreachable by any
# profile knob - `openssl-src` pins its own `-O2` - and dropping it would add a
# runtime `libcrypto` dependency, which is exactly what the AppImage's
# bundles-no-libraries invariant forbids.
[profile.release]
lto = "fat"
codegen-units = 1