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Reworked setting of bash JAVA_HOME #106

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Reworked setting of bash JAVA_HOME #106

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19 changes: 10 additions & 9 deletions set-java-home.bash
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Original file line number Diff line number Diff line change
@@ -1,19 +1,20 @@
asdf_update_java_home() {
local java_path
java_path="$(asdf which java)"
java_path="$(asdf where java)"
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@halcyon halcyon Jul 31, 2020 •
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This might be ok - the reason we switched to which is because it behaves differently when the jdk is set to system.

  % asdf where java
System version is selected
  % asdf which java                                                                                                                                     
/usr/bin/java

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@sqtran sqtran Jul 31, 2020

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It seems like the call to asdf itself is what's slowing things down, so using the where command suffers the same lag. I wonder if there is some sort of callback that we can subscribe to when asdf identifies that it needs to use a new .tools-version.

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@sqtran sqtran Jul 31, 2020

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Just to follow up on my last train of thought. The callback option may not actually work because the tool versions are "not known" until the shims are actually executed. So when calling something like java -version, asdf doesn't know which installed Java to use until at that very moment. If we were saving the last known Java version somewhere, we could potentially be out of sync because we may have traversed to a different folder already. A callback would not be able to keep the JAVA_HOME up-to-date in the same manner.

So to summarize, this is a pretty tough nut to crack. @smorimoto reviewed my PRs in the past; maybe they could weigh in?

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@jsmestad jsmestad Aug 10, 2020

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I had to update this to work when no java is available otherwise JAVA_HOME would get set to whatever asdf where java was outputting.

asdf_update_java_home() {
	local java_path
	if (asdf where java >/dev/null 2>&1); then
		java_path="$(asdf where java)"

		if [[ -n "${java_path}" ]]; then
			export JAVA_HOME
			JAVA_HOME="${java_path}"
		fi
	fi
}

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@bdellegrazie bdellegrazie Dec 23, 2020 •
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@jsmestad / @halcyon :
This may be a stupid question and I apologise if it is but why are you exporting JAVA_HOME before setting it rather than after?

if [[ -n "${java_path}" ]]; then
export JAVA_HOME
JAVA_HOME="$(dirname "$(dirname "$(realpath "${java_path}")")")"
JAVA_HOME="${java_path}"
fi
}

prompt_command() {
if [[ "${PWD}" == "${LAST_PWD}" ]]; then
return
fi
LAST_PWD="${PWD}"
preexec () {
asdf_update_java_home
}

export PROMPT_COMMAND="${PROMPT_COMMAND:+${PROMPT_COMMAND}; prompt_command}"
export PROMPT_COMMAND="${PROMPT_COMMAND:-prompt_command}"
preexec_invoke_exec () {
[ -n "${COMP_LINE}" ] && return # do nothing if completing
[ "${BASH_COMMAND}" = "${PROMPT_COMMAND}" ] && return # don't cause a preexec for $PROMPT_COMMAND
preexec
}

trap 'preexec_invoke_exec' DEBUG