From 82ffb2ecb52f750de1e505642a0bef051f5f979b Mon Sep 17 00:00:00 2001
From: Fabrizio Ferrai <fabrizio.ferrai@gmail.com>
Date: Fri, 15 Feb 2019 16:09:24 +0200
Subject: [PATCH] Add 'spago freeze' to compute hashes on the package set
 (#113)

---
 README.md               | 28 ++++++++++++++++++++++++++++
 app/Main.hs             |  9 +++++++++
 app/Spago/Messages.hs   |  6 ++++++
 app/Spago/PackageSet.hs |  8 ++++++++
 app/Spago/Packages.hs   |  1 +
 5 files changed, 52 insertions(+)

diff --git a/README.md b/README.md
index 272e18f59..7e3e17740 100644
--- a/README.md
+++ b/README.md
@@ -26,6 +26,7 @@ PureScript package manager and build tool powered by [Dhall][dhall] and
     - [Adding and overriding dependencies in the Package Set](#adding-and-overriding-dependencies-in-the-package-set)
     - [Verifying your additions and overrides](#verifying-your-additions-and-overrides)
     - [Upgrading the Package Set](#upgrading-the-package-set)
+    - [Caching the Package Set](#caching-the-package-set)
   - [Building, bundling and testing a project](#building-bundling-and-testing-a-project)
 - [FAQ](#faq)
     - [Hey wait we have a perfectly functional `pulp` right?](#hey-wait-we-have-a-perfectly-functional-pulp-right)
@@ -351,6 +352,32 @@ Fetching the new one and generating hashes.. (this might take some time)
 Done. Updating the local package-set file..
 ```
 
+#### Caching the Package Set
+
+It is important to have the hashes set in your `packages.dhall`, like this:
+
+```haskell
+...
+
+let mkPackage =
+      https://raw.githubusercontent.com/spacchetti/spacchetti/0.12.2-20190210/src/mkPackage.dhall sha256:0b197efa1d397ace6eb46b243ff2d73a3da5638d8d0ac8473e8e4a8fc528cf57
+
+let upstream =
+      https://raw.githubusercontent.com/spacchetti/spacchetti/0.12.2-20190210/src/packages.dhall sha256:1bee3f7608ca0f87a88b4b8807cb6722ab9ce3386b68325fbfa71d7211c1cf51
+
+...
+```
+
+The reason why it's so important is that (apart from [the safety guarantees][dhall-hash-safety])
+when your imports are protected by a hash they will be cached, considerably speeding up all
+the config-related operations.
+
+You can freeze the imports in your package set by running:
+
+```bash
+$ spago freeze
+```
+
 ### Building, bundling and testing a project
 
 We can build the project and its dependencies by running:
@@ -554,3 +581,4 @@ We have two commands for it:
 [todomvc]: https://github.com/f-f/purescript-react-basic-todomvc
 [purec]: https://github.com/pure-c/purec
 [purerl]: https://github.com/purerl/purescript
+[dhall-hash-safety]: https://github.com/dhall-lang/dhall-lang/wiki/Safety-guarantees#code-injection
diff --git a/app/Main.hs b/app/Main.hs
index 63bf4f735..2e41a284b 100644
--- a/app/Main.hs
+++ b/app/Main.hs
@@ -57,6 +57,9 @@ data Command
   -- | Upgrade the package-set to the latest release
   | SpacchettiUpgrade
 
+  -- | Freeze the package-set so it will be cached
+  | Freeze
+
   -- | ### Commands for working with Psc-Package
   --
   --   Do the boilerplate of the local project setup to override and add arbitrary packages
@@ -96,6 +99,7 @@ parser
   T.<|> bundle
   T.<|> makeModule
   T.<|> spacchettiUpgrade
+  T.<|> freeze
   T.<|> pscPackageLocalSetup
   T.<|> pscPackageInsDhall
   T.<|> pscPackageClean
@@ -176,6 +180,10 @@ parser
       = T.subcommand "spacchetti-upgrade" "Upgrade the upstream in packages.dhall to the latest Spacchetti release"
       $ pure SpacchettiUpgrade
 
+    freeze
+      = T.subcommand "freeze" "Add hashes to the package-set, so it will be cached"
+      $ pure Freeze
+
     version
       = T.subcommand "version" "Show spago version"
       $ pure Version
@@ -201,6 +209,7 @@ main = do
     Verify limitJobs package              -> Spago.Packages.verify limitJobs (Just package)
     VerifySet limitJobs                   -> Spago.Packages.verify limitJobs Nothing
     SpacchettiUpgrade                     -> Spago.Packages.upgradeSpacchetti
+    Freeze                                -> Spago.Packages.freeze
     Build limitJobs paths pursArgs        -> Spago.Build.build limitJobs paths pursArgs
     Test modName limitJobs paths pursArgs -> Spago.Build.test modName limitJobs paths pursArgs
     Repl paths pursArgs                   -> Spago.Build.repl paths pursArgs
diff --git a/app/Spago/Messages.hs b/app/Spago/Messages.hs
index e09ac9db1..31d380b5b 100644
--- a/app/Spago/Messages.hs
+++ b/app/Spago/Messages.hs
@@ -83,6 +83,12 @@ upgradingPackageSet newTag = makeMessage
   , "Fetching the new one and generating hashes.. (this might take some time)"
   ]
 
+freezePackageSet :: Text
+freezePackageSet = makeMessage
+  [ "Generating hashes for the package-set so it will be cached."
+  , "This might take some time..."
+  ]
+
 packageSetVersionWarning :: Text
 packageSetVersionWarning = makeMessage
  [ "WARNING: the package-set version you're on doesn't check if the version of the"
diff --git a/app/Spago/PackageSet.hs b/app/Spago/PackageSet.hs
index 80bcc41f7..2aa690938 100644
--- a/app/Spago/PackageSet.hs
+++ b/app/Spago/PackageSet.hs
@@ -2,6 +2,7 @@ module Spago.PackageSet
   ( upgradeSpacchetti
   , checkPursIsUpToDate
   , makePackageSetFile
+  , freeze
   , path
   , pathText
   , PackageSet
@@ -93,6 +94,13 @@ makePackageSetFile force = do
   Dhall.Format.format Dhall.Pretty.Unicode (Just $ Text.unpack pathText)
 
 
+-- | Freeze the package-set imports so they can be cached
+freeze :: IO ()
+freeze = do
+  echo Messages.freezePackageSet
+  Dhall.Freeze.freeze (Just $ Text.unpack pathText) False defaultStandardVersion
+
+
 data RawPackageSet = RawPackageSet
   { mkPackage :: Dhall.Import
   , upstream  :: Dhall.Import
diff --git a/app/Spago/Packages.hs b/app/Spago/Packages.hs
index 48ff966f1..e67b36706 100644
--- a/app/Spago/Packages.hs
+++ b/app/Spago/Packages.hs
@@ -7,6 +7,7 @@ module Spago.Packages
   , getGlobs
   , getProjectDeps
   , PackageSet.upgradeSpacchetti
+  , PackageSet.freeze
   , PackageSet.PackageName(..)
   , PackagesFilter(..)
   ) where