# Copyright 2012-2020 Free Software Foundation, Inc.

# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.


# The in-memory cache.
array set gdb_data_cache {}

# Print pass message msg into gdb.log
proc ignore_pass { msg } {
    verbose -log "gdb_do_cache_wrap ignoring pass: $msg"
}

# Call proc real_name and return the result, while ignoring calls to pass.
proc gdb_do_cache_wrap {real_name} {
    if { [info procs save_pass] != "" } {
	return [uplevel 2 $real_name]
    }

    rename pass save_pass
    rename ignore_pass pass

    set code [catch {uplevel 2 $real_name} result]

    rename pass ignore_pass
    rename save_pass pass

    if {$code == 1} {
	global errorInfo errorCode
	return -code error -errorinfo $errorInfo -errorcode $errorCode $result
    } elseif {$code > 1} {
	return -code $code $result
    }

    return $result
}

# A helper for gdb_caching_proc that handles the caching.

proc gdb_do_cache {name} {
    global gdb_data_cache objdir
    global GDB_PARALLEL

    # Normally, if we have a cached value, we skip computation and return
    # the cached value.  If set to 1, instead don't skip computation and
    # verify against the cached value.
    set cache_verify 0

    # Alternatively, set this to do cache_verify only for one proc.
    set cache_verify_proc ""
    if { $name == $cache_verify_proc } {
	set cache_verify 1
    }

    # See if some other process wrote the cache file.  Cache value per
    # "board" to handle runs with multiple options
    # (e.g. unix/{-m32,-64}) correctly.  We use "file join" here
    # because we later use this in a real filename.
    set cache_name [file join [target_info name] $name]

    set is_cached 0
    if {[info exists gdb_data_cache($cache_name)]} {
	set cached $gdb_data_cache($cache_name)
	verbose "$name: returning '$cached' from cache" 2
	if { $cache_verify == 0 } {
	    return $cached
	}
	set is_cached 1
    }

    if { $is_cached == 0 && [info exists GDB_PARALLEL] } {
	set cache_filename [make_gdb_parallel_path cache $cache_name]
	if {[file exists $cache_filename]} {
	    set fd [open $cache_filename]
	    set gdb_data_cache($cache_name) [read -nonewline $fd]
	    close $fd
	    set cached $gdb_data_cache($cache_name)
	    verbose "$name: returning '$cached' from file cache" 2
	    if { $cache_verify == 0 } {
		return $cached
	    }
	    set is_cached 1
	}
    }

    set real_name gdb_real__$name
    set gdb_data_cache($cache_name) [gdb_do_cache_wrap $real_name]
    if { $cache_verify == 1 && $is_cached == 1 } {
	set computed $gdb_data_cache($cache_name)
	if { $cached != $computed } {
	    error [join [list "Inconsistent results for $cache_name:"
			 "cached: $cached vs. computed: $computed"]]
	}
    }

    if {[info exists GDB_PARALLEL]} {
	verbose "$name: returning '$gdb_data_cache($cache_name)' and writing file" 2
	file mkdir [file dirname $cache_filename]
	# Make sure to write the results file atomically.
	set fd [open $cache_filename.[pid] w]
	puts $fd $gdb_data_cache($cache_name)
	close $fd
	file rename -force -- $cache_filename.[pid] $cache_filename
    }
    return $gdb_data_cache($cache_name)
}

# Define a new proc named NAME that takes no arguments.  BODY is the
# body of the proc.  The proc will evaluate BODY and cache the
# results, both in memory and, if GDB_PARALLEL is defined, in the
# filesystem for use across invocations of dejagnu.

proc gdb_caching_proc {name body} {
    # Define the underlying proc that we'll call.
    set real_name gdb_real__$name
    proc $real_name {} $body

    # Define the advertised proc.
    proc $name {} [list gdb_do_cache $name]
}