[OE-core] [PATCH 2/4] ccache.bbclass: Refactor it to make it more reliable

[Richard Purdie]

On Sun, 2018-12-09 at 18:24 -0800, Robert Yang wrote:
> The previous ccache.bbclass has the following problems:
> - It uses host's ccache for native recipes, but this may not work on some
>   hosts, for example, it nerver works on my Ubuntu 14.04.4, there are always
>   build failures (m4-native failed at do_configure, and others will also be
>   failed if I disable CCACHE for m4-native)
> 
> - native/nativesdk/cross/crosssdk recipes use host's ccahe, but target uses
>   ccache-native, this may confuse user.
> 
> - The target recipes may use both host's ccache and ccache-native, this may
>   cause unexpected problems and hard to debug. This is because ccache-native is
>   in SIGGEN_EXCLUDE_SAFE_RECIPE_DEPS, so ccache-native may not be present when
>   rebuild target recipes, and then it would use hosttools/ccache, but the
>   previous ccache files were generated by ccache-native.
> 
> - Target recipes can't use ccache when no ccahe is installed on the host:
>   CCACHE = "${@bb.utils.which(d.getVar('PATH'), 'ccache') and 'ccache '}"
> 
> After refactored:
> All types recipes (native, target and others) will use ccache-native except
> ccache-native's dependencies, host's cache won't be used any more. It is more
> reliable now, which will work everywhere when ccache-native can be built.
> 
> And now we need use "CCACHE_DISABLE = '1'" to disable ccahe for the recipe
> rather than "CCACHE = ''" since we set CCACHE in anonymous function, and
> d.getVar('CCACHE') works after "CCACHE ??=" which is set in bitbake.conf, so we
> can't check whether CCACHE is set or not in anonymous function since it is
> always set. Use CCACHE_DISABLE to disable it would be more clear.
> 
> Signed-off-by: Robert Yang <liezhi.yang at windriver.com>
> ---
>  meta/classes/ccache.bbclass             | 25 ++++++++++++++++++++++---
>  meta/conf/bitbake.conf                  | 21 ++++++++++++++++-----
>  meta/conf/layer.conf                    |  1 -
>  meta/lib/oe/utils.py                    |  3 +++
>  meta/recipes-devtools/ccache/ccache.inc |  2 ++
>  5 files changed, 43 insertions(+), 9 deletions(-)
> 
> diff --git a/meta/classes/ccache.bbclass b/meta/classes/ccache.bbclass
> index 9609020..f4eefce 100644
> --- a/meta/classes/ccache.bbclass
> +++ b/meta/classes/ccache.bbclass
> @@ -1,4 +1,14 @@
> -CCACHE = "${@bb.utils.which(d.getVar('PATH'), 'ccache') and 'ccache '}"
> +#
> +# Usage:
> +# - Enable ccache
> +#   Add the following line to a conffile such as conf/local.conf:
> +#   INHERIT += "ccache"
> +#
> +# - Disable ccache for a recipe
> +#   Add the following line to the recipe if it can't be built with ccache:
> +#   CCACHE_DISABLE = '1'
> +#
> +
>  export CCACHE_DIR ?= "${TMPDIR}/ccache/${MULTIMACH_TARGET_SYS}/${PN}"
>  
>  # We need to stop ccache considering the current directory or the
> @@ -7,5 +17,14 @@ export CCACHE_DIR ?= "${TMPDIR}/ccache/${MULTIMACH_TARGET_SYS}/${PN}"
>  # ${PV} or ${PR} change.
>  export CCACHE_NOHASHDIR ?= "1"
>  
> -DEPENDS_append_class-target = " ccache-native"
> -DEPENDS[vardepvalueexclude] = " ccache-native"
> +python() {
> +    """
> +    Enable ccache for the recipe if is not a dependency of ccache-native
> +    """
> +    ccache_native_deps = d.getVar('CCACHE_NATIVE_DEPENDS') or ''
> +    ccache_native_deps += 'ccache-native'
> +    if not (d.getVar('PN') in ccache_native_deps.split() or \
> +            bb.utils.to_boolean(d.getVar('CCACHE_DISABLE'))):
> +        d.appendVar('DEPENDS', ' ccache-native')
> +        d.setVar('CCACHE', 'ccache ')
> +}
> diff --git a/meta/conf/bitbake.conf b/meta/conf/bitbake.conf
> index 6480062..cb1dba8 100644
> --- a/meta/conf/bitbake.conf
> +++ b/meta/conf/bitbake.conf
> @@ -492,7 +492,7 @@ HOSTTOOLS += " \
>  HOSTTOOLS += "${@'ip ping ps scp ssh stty' if (bb.utils.contains_any('IMAGE_CLASSES', 'testimage testsdk', True, False, d) or any(x in (d.getVar("BBINCLUDED") or "") for x in ["testimage.bbclass", "testsdk.bbclass"])) else ''}"
>  
>  # Link to these if present
> -HOSTTOOLS_NONFATAL += "aws ccache gcc-ar gpg ld.bfd ld.gold nc pigz sftp socat ssh sudo"
> +HOSTTOOLS_NONFATAL += "aws gcc-ar gpg ld.bfd ld.gold nc pigz sftp socat ssh sudo"
>  
>  # Temporary add few more detected in bitbake world
>  HOSTTOOLS_NONFATAL += "join nl size yes zcat"
> @@ -503,11 +503,22 @@ HOSTTOOLS_NONFATAL += "bzr"
>  # Used by ssh fetcher
>  HOSTTOOLS_NONFATAL += "scp"
>  
> +# This is used by both ccache.bbclass and ccahe-native recipe, these
> +# recipes can't use ccache since ccache-native depends on them,
> +# otherwise, there would be loop dependencies.
> +CCACHE_NATIVE_DEPENDS ?= " \
> +    gnu-config-native \
> +    autoconf-native \
> +    quilt-native \
> +    zlib-native \
> +    gettext-minimal-native \
> +    texinfo-dummy-native \
> +    m4-native \
> +    libtool-native \
> +    automake-native \
> +    xz-native \
> +"
>  CCACHE ??= ""
> -# ccache < 3.1.10 will create CCACHE_DIR on startup even if disabled, and
> -# autogen sets HOME=/dev/null so in certain situations builds can fail.
> -# Explicitly export CCACHE_DIR until we can assume ccache >3.1.10 on the host.
> -export CCACHE_DIR ??= "${@os.getenv('HOME')}/.ccache"

Hardcoding a list of ccache-native dependencies is horrible and I do
not want to do that. 

Also, I want to stop the build up of unneeded 'stuff' in bitbake.conf.
We should start making better use of inc files.

Please also ensure that the oe-selftest ccache tests continue to work
after these changes. I haven't checked specifically here but we've had
a lot of trouble with that before.

Cheers,

Richard