trace2: rename environment variables to GIT_TRACE2*

For an environment variable that is supposed to be set by users, the
GIT_TR2* env vars are just too unclear, inconsistent, and ugly.

Most of the established GIT_* environment variables don't use
abbreviations, and in case of the few that do (GIT_DIR,
GIT_COMMON_DIR, GIT_DIFF_OPTS) it's quite obvious what the
abbreviations (DIR and OPTS) stand for.  But what does TR stand for?
Track, traditional, trailer, transaction, transfer, transformation,
transition, translation, transplant, transport, traversal, tree,
trigger, truncate, trust, or ...?!

The trace2 facility, as the '2' suffix in its name suggests, is
supposed to eventually supercede Git's original trace facility.  It's
reasonable to expect that the corresponding environment variables
follow suit, and after the original GIT_TRACE variables they are
called GIT_TRACE2; there is no such thing is 'GIT_TR'.

All trace2-specific config variables are, very sensibly, in the
'trace2' section, not in 'tr2'.

OTOH, we don't gain anything at all by omitting the last three
characters of "trace" from the names of these environment variables.

So let's rename all GIT_TR2* environment variables to GIT_TRACE2*,
before they make their way into a stable release.

Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/config/trace2.txt

@@ -4,53 +4,53 @@ command line arguments are not respected.
 
 trace2.normalTarget::
 	This variable controls the normal target destination.
-	It may be overridden by the `GIT_TR2` environment variable.
+	It may be overridden by the `GIT_TRACE2` environment variable.
 	The following table shows possible values.
 
 trace2.perfTarget::
 	This variable controls the performance target destination.
-	It may be overridden by the `GIT_TR2_PERF` environment variable.
+	It may be overridden by the `GIT_TRACE2_PERF` environment variable.
 	The following table shows possible values.
 
 trace2.eventTarget::
 	This variable controls the event target destination.
-	It may be overridden by the `GIT_TR2_EVENT` environment variable.
+	It may be overridden by the `GIT_TRACE2_EVENT` environment variable.
 	The following table shows possible values.
 +
 include::../trace2-target-values.txt[]
 
 trace2.normalBrief::
 	Boolean.  When true `time`, `filename`, and `line` fields are
 	omitted from normal output.  May be overridden by the
-	`GIT_TR2_BRIEF` environment variable.  Defaults to false.
+	`GIT_TRACE2_BRIEF` environment variable.  Defaults to false.
 
 trace2.perfBrief::
 	Boolean.  When true `time`, `filename`, and `line` fields are
 	omitted from PERF output.  May be overridden by the
-	`GIT_TR2_PERF_BRIEF` environment variable.  Defaults to false.
+	`GIT_TRACE2_PERF_BRIEF` environment variable.  Defaults to false.
 
 trace2.eventBrief::
 	Boolean.  When true `time`, `filename`, and `line` fields are
 	omitted from event output.  May be overridden by the
-	`GIT_TR2_EVENT_BRIEF` environment variable.  Defaults to false.
+	`GIT_TRACE2_EVENT_BRIEF` environment variable.  Defaults to false.
 
 trace2.eventNesting::
 	Integer.  Specifies desired depth of nested regions in the
 	event output.  Regions deeper than this value will be
-	omitted.  May be overridden by the `GIT_TR2_EVENT_NESTING`
+	omitted.  May be overridden by the `GIT_TRACE2_EVENT_NESTING`
 	environment variable.  Defaults to 2.
 
 trace2.configParams::
 	A comma-separated list of patterns of "important" config
 	settings that should be recorded in the trace2 output.
 	For example, `core.*,remote.*.url` would cause the trace2
 	output to contain events listing each configured remote.
-	May be overridden by the `GIT_TR2_CONFIG_PARAMS` environment
+	May be overridden by the `GIT_TRACE2_CONFIG_PARAMS` environment
 	variable.  Unset by default.
 
 trace2.destinationDebug::
 	Boolean.  When true Git will print error messages when a
 	trace target destination cannot be opened for writing.
 	By default, these errors are suppressed and tracing is
 	silently disabled.  May be overridden by the
-	`GIT_TR2_DST_DEBUG` environment variable.
+	`GIT_TRACE2_DST_DEBUG` environment variable.

Documentation/git.txt

@@ -660,23 +660,23 @@ of clones and fetches.
 	When a curl trace is enabled (see `GIT_TRACE_CURL` above), do not dump
 	data (that is, only dump info lines and headers).
 
-`GIT_TR2`::
+`GIT_TRACE2`::
 	Enables more detailed trace messages from the "trace2" library.
-	Output from `GIT_TR2` is a simple text-based format for human
+	Output from `GIT_TRACE2` is a simple text-based format for human
 	readability.
 +
-The `GIT_TR2` variables can take many values. Any value available to
-the `GIT_TRACE` variables is also available to `GIT_TR2`. The `GIT_TR2`
+The `GIT_TRACE2` variables can take many values. Any value available to
+the `GIT_TRACE` variables is also available to `GIT_TRACE2`. The `GIT_TRACE2`
 variables can also specify a Unix Domain Socket. See
 link:technical/api-trace2.html[Trace2 documentation] for full details.
 
-`GIT_TR2_EVENT`::
+`GIT_TRACE2_EVENT`::
 	This setting writes a JSON-based format that is suited for machine
 	interpretation. See link:technical/api-trace2.html[Trace2 documentation]
 	for full details.
 
-`GIT_TR2_PERF`::
-	In addition to the text-based messages available in `GIT_TR2`, this
+`GIT_TRACE2_PERF`::
+	In addition to the text-based messages available in `GIT_TRACE2`, this
 	setting writes a column-based format for understanding nesting
 	regions. See link:technical/api-trace2.html[Trace2 documentation]
 	for full details.

Documentation/technical/api-trace2.txt

@@ -23,7 +23,7 @@ formats in the future.  This might be used to define a binary format,
 for example.
 
 Trace2 is controlled using `trace2.*` config values in the system and
-global config files and `GIT_TR2*` environment variables.  Trace2 does
+global config files and `GIT_TRACE2*` environment variables.  Trace2 does
 not read from repo local or worktree config files or respect `-c`
 command line config settings.
 
@@ -42,7 +42,7 @@ config setting.
 For example
 
 ------------
-$ export GIT_TR2=~/log.normal
+$ export GIT_TRACE2=~/log.normal
 $ git version
 git version 2.20.1.155.g426c96fcdb
 ------------
@@ -71,13 +71,13 @@ $ cat ~/log.normal
 The performance format target (PERF) is a column-based format to
 replace GIT_TRACE_PERFORMANCE and is suitable for development and
 testing, possibly to complement tools like gprof.  This format is
-enabled with the `GIT_TR2_PERF` environment variable or the
+enabled with the `GIT_TRACE2_PERF` environment variable or the
 `trace2.perfTarget` system or global config setting.
 
 For example
 
 ------------
-$ export GIT_TR2_PERF=~/log.perf
+$ export GIT_TRACE2_PERF=~/log.perf
 $ git version
 git version 2.20.1.155.g426c96fcdb
 ------------
@@ -104,14 +104,14 @@ $ cat ~/log.perf
 === The Event Format Target
 
 The event format target is a JSON-based format of event data suitable
-for telemetry analysis.  This format is enabled with the `GIT_TR2_EVENT`
+for telemetry analysis.  This format is enabled with the `GIT_TRACE2_EVENT`
 environment variable or the `trace2.eventTarget` system or global config
 setting.
 
 For example
 
 ------------
-$ export GIT_TR2_EVENT=~/log.event
+$ export GIT_TRACE2_EVENT=~/log.event
 $ git version
 git version 2.20.1.155.g426c96fcdb
 ------------
@@ -273,7 +273,7 @@ significantly affects program performance or behavior, such as
 	Emits a "def_param" messages for "important" configuration
 	settings.
 +
-The environment variable `GIT_TR2_CONFIG_PARAMS` or the `trace2.configParams`
+The environment variable `GIT_TRACE2_CONFIG_PARAMS` or the `trace2.configParams`
 config value can be set to a
 list of patterns of important configuration settings, for example:
 `core.*,remote.*.url`.  This function will iterate over all config
@@ -465,7 +465,7 @@ Events are written as lines of the form:
 Note that this may contain embedded LF or CRLF characters that are
 not escaped, so the event may spill across multiple lines.
 
-If `GIT_TR2_BRIEF` or `trace2.normalBrief` is true, the `time`, `filename`,
+If `GIT_TRACE2_BRIEF` or `trace2.normalBrief` is true, the `time`, `filename`,
 and `line` fields are omitted.
 
 This target is intended to be more of a summary (like GIT_TRACE) and
@@ -533,7 +533,7 @@ This field is in anticipation of in-proc submodules in the future.
 15:33:33.532712 wt-status.c:2331                  | d0 | main                     | region_leave | r1  |  0.127568 |  0.001504 | status     | label:print
 ------------
 
-If `GIT_TR2_PERF_BRIEF` or `trace2.perfBrief` is true, the `time`, `file`,
+If `GIT_TRACE2_PERF_BRIEF` or `trace2.perfBrief` is true, the `time`, `file`,
 and `line` fields are omitted.
 
 ------------
@@ -598,7 +598,7 @@ The following key/value pairs are common to all events:
 `"repo":<repo-id>`::
 	when present, is the integer repo-id as described previously.
 
-If `GIT_TR2_EVENT_BRIEF` or `trace2.eventBrief` is true, the `file`
+If `GIT_TRACE2_EVENT_BRIEF` or `trace2.eventBrief` is true, the `file`
 and `line` fields are omitted from all events and the `time` field is
 only present on the "start" and "atexit" events.
 
@@ -911,7 +911,7 @@ visited.
 The `category` field may be used in a future enhancement to
 do category-based filtering.
 +
-`GIT_TR2_EVENT_NESTING` or `trace2.eventNesting` can be used to
+`GIT_TRACE2_EVENT_NESTING` or `trace2.eventNesting` can be used to
 filter deeply nested regions and data events.  It defaults to "2".
 
 `"region_leave"`::
@@ -1039,8 +1039,8 @@ rev-list, and gc.  This example also shows that fetch took
 5.199 seconds and of that 4.932 was in ssh.
 +
 ----------------
-$ export GIT_TR2_BRIEF=1
-$ export GIT_TR2=~/log.normal
+$ export GIT_TRACE2_BRIEF=1
+$ export GIT_TRACE2=~/log.normal
 $ git fetch origin
 ...
 ----------------
@@ -1075,8 +1075,8 @@ its name as "gc", it also reports the hierarchy as "fetch/gc".
 indented for clarity.)
 +
 ----------------
-$ export GIT_TR2_BRIEF=1
-$ export GIT_TR2=~/log.normal
+$ export GIT_TRACE2_BRIEF=1
+$ export GIT_TRACE2=~/log.normal
 $ git fetch origin
 ...
 ----------------
@@ -1134,8 +1134,8 @@ In this example, scanning for untracked files ran from +0.012568 to
 +0.027149 (since the process started) and took 0.014581 seconds.
 +
 ----------------
-$ export GIT_TR2_PERF_BRIEF=1
-$ export GIT_TR2_PERF=~/log.perf
+$ export GIT_TRACE2_PERF_BRIEF=1
+$ export GIT_TRACE2_PERF=~/log.perf
 $ git status
 ...
 
@@ -1180,8 +1180,8 @@ static enum path_treatment read_directory_recursive(struct dir_struct *dir,
 We can further investigate the time spent scanning for untracked files.
 +
 ----------------
-$ export GIT_TR2_PERF_BRIEF=1
-$ export GIT_TR2_PERF=~/log.perf
+$ export GIT_TRACE2_PERF_BRIEF=1
+$ export GIT_TRACE2_PERF=~/log.perf
 $ git status
 ...
 $ cat ~/log.perf
@@ -1236,8 +1236,8 @@ int read_index_from(struct index_state *istate, const char *path,
 This example shows that the index contained 3552 entries.
 +
 ----------------
-$ export GIT_TR2_PERF_BRIEF=1
-$ export GIT_TR2_PERF=~/log.perf
+$ export GIT_TRACE2_PERF_BRIEF=1
+$ export GIT_TRACE2_PERF=~/log.perf
 $ git status
 ...
 $ cat ~/log.perf
@@ -1310,8 +1310,8 @@ Data events are tagged with the active thread name.  They are used
 to report the per-thread parameters.
 +
 ----------------
-$ export GIT_TR2_PERF_BRIEF=1
-$ export GIT_TR2_PERF=~/log.perf
+$ export GIT_TRACE2_PERF_BRIEF=1
+$ export GIT_TRACE2_PERF=~/log.perf
 $ git status
 ...
 $ cat ~/log.perf

t/t0001-init.sh

@@ -93,7 +93,7 @@ test_expect_success 'No extra GIT_* on alias scripts' '
 		sed -n \
 			-e "/^GIT_PREFIX=/d" \
 			-e "/^GIT_TEXTDOMAINDIR=/d" \
-			-e "/^GIT_TR2_PARENT/d" \
+			-e "/^GIT_TRACE2_PARENT/d" \
 			-e "/^GIT_/s/=.*//p" |
 		sort
 	EOF

t/t0210-trace2-normal.sh

@@ -4,9 +4,9 @@ test_description='test trace2 facility (normal target)'
 . ./test-lib.sh
 
 # Turn off any inherited trace2 settings for this test.
-sane_unset GIT_TR2 GIT_TR2_PERF GIT_TR2_EVENT
-sane_unset GIT_TR2_BRIEF
-sane_unset GIT_TR2_CONFIG_PARAMS
+sane_unset GIT_TRACE2 GIT_TRACE2_PERF GIT_TRACE2_EVENT
+sane_unset GIT_TRACE2_BRIEF
+sane_unset GIT_TRACE2_CONFIG_PARAMS
 
 # Add t/helper directory to PATH so that we can use a relative
 # path to run nested instances of test-tool.exe (see 004child).
@@ -27,12 +27,12 @@ V=$(git version | sed -e 's/^git version //') && export V
 # to whatever filtering that target decides to do).
 # This script tests the normal target in isolation.
 #
-# Defer setting GIT_TR2 until the actual command line we want to test
+# Defer setting GIT_TRACE2 until the actual command line we want to test
 # because hidden git and test-tool commands run by the test harness
 # can contaminate our output.
 
 # Enable "brief" feature which turns off "<clock> <file>:<line> " prefix.
-GIT_TR2_BRIEF=1 && export GIT_TR2_BRIEF
+GIT_TRACE2_BRIEF=1 && export GIT_TRACE2_BRIEF
 
 # Basic tests of the trace2 normal stream.  Since this stream is used
 # primarily with printf-style debugging/tracing, we do limited testing
@@ -54,7 +54,7 @@ GIT_TR2_BRIEF=1 && export GIT_TR2_BRIEF
 
 test_expect_success 'normal stream, return code 0' '
 	test_when_finished "rm trace.normal actual expect" &&
-	GIT_TR2="$(pwd)/trace.normal" test-tool trace2 001return 0 &&
+	GIT_TRACE2="$(pwd)/trace.normal" test-tool trace2 001return 0 &&
 	perl "$TEST_DIRECTORY/t0210/scrub_normal.perl" <trace.normal >actual &&
 	cat >expect <<-EOF &&
 		version $V
@@ -68,7 +68,7 @@ test_expect_success 'normal stream, return code 0' '
 
 test_expect_success 'normal stream, return code 1' '
 	test_when_finished "rm trace.normal actual expect" &&
-	test_must_fail env GIT_TR2="$(pwd)/trace.normal" test-tool trace2 001return 1 &&
+	test_must_fail env GIT_TRACE2="$(pwd)/trace.normal" test-tool trace2 001return 1 &&
 	perl "$TEST_DIRECTORY/t0210/scrub_normal.perl" <trace.normal >actual &&
 	cat >expect <<-EOF &&
 		version $V
@@ -83,7 +83,7 @@ test_expect_success 'normal stream, return code 1' '
 test_expect_success 'automatic filename' '
 	test_when_finished "rm -r traces actual expect" &&
 	mkdir traces &&
-	GIT_TR2="$(pwd)/traces" test-tool trace2 001return 0 &&
+	GIT_TRACE2="$(pwd)/traces" test-tool trace2 001return 0 &&
 	perl "$TEST_DIRECTORY/t0210/scrub_normal.perl" <"$(ls traces/*)" >actual &&
 	cat >expect <<-EOF &&
 		version $V
@@ -101,7 +101,7 @@ test_expect_success 'automatic filename' '
 
 test_expect_success 'normal stream, exit code 0' '
 	test_when_finished "rm trace.normal actual expect" &&
-	GIT_TR2="$(pwd)/trace.normal" test-tool trace2 002exit 0 &&
+	GIT_TRACE2="$(pwd)/trace.normal" test-tool trace2 002exit 0 &&
 	perl "$TEST_DIRECTORY/t0210/scrub_normal.perl" <trace.normal >actual &&
 	cat >expect <<-EOF &&
 		version $V
@@ -115,7 +115,7 @@ test_expect_success 'normal stream, exit code 0' '
 
 test_expect_success 'normal stream, exit code 1' '
 	test_when_finished "rm trace.normal actual expect" &&
-	test_must_fail env GIT_TR2="$(pwd)/trace.normal" test-tool trace2 002exit 1 &&
+	test_must_fail env GIT_TRACE2="$(pwd)/trace.normal" test-tool trace2 002exit 1 &&
 	perl "$TEST_DIRECTORY/t0210/scrub_normal.perl" <trace.normal >actual &&
 	cat >expect <<-EOF &&
 		version $V
@@ -133,7 +133,7 @@ test_expect_success 'normal stream, exit code 1' '
 
 test_expect_success 'normal stream, error event' '
 	test_when_finished "rm trace.normal actual expect" &&
-	GIT_TR2="$(pwd)/trace.normal" test-tool trace2 003error "hello world" "this is a test" &&
+	GIT_TRACE2="$(pwd)/trace.normal" test-tool trace2 003error "hello world" "this is a test" &&
 	perl "$TEST_DIRECTORY/t0210/scrub_normal.perl" <trace.normal >actual &&
 	cat >expect <<-EOF &&
 		version $V
@@ -147,7 +147,7 @@ test_expect_success 'normal stream, error event' '
 	test_cmp expect actual
 '
 
-sane_unset GIT_TR2_BRIEF
+sane_unset GIT_TRACE2_BRIEF
 
 # Now test without environment variables and get all Trace2 settings
 # from the global config.