defer searching $PATH for vcexe until later; better errors

Before this change, a missing vcexe would cause something like

    exceptions.RuntimeError: Couldn't find executable for 'hg'

With this change, a missing vcexe gives something like

    could not find 'hg'
    PATH is 'blah blah blah'
    program finished with exit code -1

Fixes #783

slave/buildslave/commands/base.py

@@ -1,6 +1,7 @@
 
 import os, signal, types, re, traceback
 from stat import ST_CTIME, ST_MTIME, ST_SIZE
+import os
 import sys
 import shutil
 
@@ -230,9 +231,23 @@ def setup(self, args):
         self.timeout = args.get('timeout', 120)
         self.maxTime = args.get('maxTime', None)
         self.retry = args.get('retry')
+        self._commandPaths = {}
         # VC-specific subclasses should override this to extract more args.
         # Make sure to upcall!
 
+    def getCommand(self, name):
+        """Wrapper around utils.getCommand that will output a resonable
+        error message and raise AbandonChain if the command cannot be
+        found"""
+        if name not in self._commandPaths:
+            try:
+                self._commandPaths[name] = utils.getCommand(name)
+            except RuntimeError:
+                self.sendStatus({'stderr' : "could not find '%s'\n" % name})
+                self.sendStatus({'stderr' : "PATH is '%s'\n" % os.environ.get('PATH', '')})
+                raise AbandonChain(-1)
+        return self._commandPaths[name]
+
     def start(self):
         self.sendStatus({'header': "starting " + self.header + "\n"})
         self.command = None

slave/buildslave/commands/bk.py

@@ -18,7 +18,6 @@ class BK(SourceBaseCommand):
 
     def setup(self, args):
         SourceBaseCommand.setup(self, args)
-        self.vcexe = utils.getCommand("bk")
         self.bkurl = args['bkurl']
         self.sourcedata = '"%s\n"' % self.bkurl
 
@@ -34,27 +33,29 @@ def sourcedirIsUpdateable(self):
                                           self.srcdir, "BK/parent"))
 
     def doVCUpdate(self):
+        bk = self.getCommand('bk')
         revision = self.args['revision'] or 'HEAD'
         # update: possible for mode in ('copy', 'update')
         d = os.path.join(self.builder.basedir, self.srcdir)
 
         # Revision is ignored since the BK free client doesn't support it.
-        command = [self.vcexe, 'pull']
+        command = [bk, 'pull']
         c = runprocess.RunProcess(self.builder, command, d,
                          sendRC=False, timeout=self.timeout,
                          keepStdout=True, usePTY=False)
         self.command = c
         return c.start()
 
     def doVCFull(self):
+        bk = self.getCommand('bk')
 
         revision_arg = ''
         if self.args['revision']:
             revision_arg = "-r%s" % self.args['revision']
 
         d = self.builder.basedir
 
-        command = [self.vcexe, 'clone', revision_arg] + self.bk_args + \
+        command = [bk, 'clone', revision_arg] + self.bk_args + \
                    [self.bkurl, self.srcdir]
         c = runprocess.RunProcess(self.builder, command, d,
                          sendRC=False, timeout=self.timeout,
@@ -69,7 +70,8 @@ def getBKVersionCommand(self):
 
         return: list of strings, passable as the command argument to RunProcess
         """
-        return [self.vcexe, "changes", "-r+", "-d:REV:"]
+        bk = self.getCommand('bk')
+        return [bk, "changes", "-r+", "-d:REV:"]
 
     def parseGotRevision(self):
         c = runprocess.RunProcess(self.builder,

slave/buildslave/commands/bzr.py

@@ -20,7 +20,6 @@ class Bzr(SourceBaseCommand):
 
     def setup(self, args):
         SourceBaseCommand.setup(self, args)
-        self.vcexe = utils.getCommand("bzr")
         self.repourl = args['repourl']
         self.sourcedata = "%s\n" % self.repourl
         self.revision = self.args.get('revision')
@@ -46,17 +45,20 @@ def cont(res):
             return cont(None)
 
     def doVCUpdate(self):
+        bzr = self.getCommand('bzr')
         assert not self.revision
         # update: possible for mode in ('copy', 'update')
         srcdir = os.path.join(self.builder.basedir, self.srcdir)
-        command = [self.vcexe, 'update']
+        command = [bzr, 'update']
         c = runprocess.RunProcess(self.builder, command, srcdir,
                          sendRC=False, timeout=self.timeout,
                          maxTime=self.maxTime, usePTY=False)
         self.command = c
         return c.start()
 
     def doVCFull(self):
+        bzr = self.getCommand('bzr')
+
         # checkout or export
         d = self.builder.basedir
         if self.mode == "export":
@@ -72,7 +74,7 @@ def doVCFull(self):
         #
         # So I won't bother using --lightweight for now.
 
-        command = [self.vcexe, 'checkout']
+        command = [bzr, 'checkout']
         if self.revision:
             command.append('--revision')
             command.append(str(self.revision))
@@ -87,9 +89,10 @@ def doVCFull(self):
         return d
 
     def doVCExport(self):
+        bzr = self.getCommand('bzr')
         tmpdir = os.path.join(self.builder.basedir, "export-temp")
         srcdir = os.path.join(self.builder.basedir, self.srcdir)
-        command = [self.vcexe, 'checkout', '--lightweight']
+        command = [bzr, 'checkout', '--lightweight']
         if self.revision:
             command.append('--revision')
             command.append(str(self.revision))
@@ -101,7 +104,7 @@ def doVCExport(self):
         self.command = c
         d = c.start()
         def _export(res):
-            command = [self.vcexe, 'export', srcdir]
+            command = [bzr, 'export', srcdir]
             c = runprocess.RunProcess(self.builder, command, tmpdir,
                              sendRC=False, timeout=self.timeout,
                              maxTime=self.maxTime, usePTY=False)
@@ -111,18 +114,20 @@ def _export(res):
         return d
 
     def doForceSharedRepo(self):
+        bzr = self.getCommand('bzr')
+
         # Don't send stderr. When there is no shared repo, this might confuse
         # users, as they will see a bzr error message. But having no shared
         # repo is not an error, just an indication that we need to make one.
-        c = runprocess.RunProcess(self.builder, [self.vcexe, 'info', '.'],
+        c = runprocess.RunProcess(self.builder, [bzr, 'info', '.'],
                          self.builder.basedir,
                          sendStderr=False, sendRC=False, usePTY=False)
         d = c.start()
         def afterCheckSharedRepo(res):
             if type(res) is int and res != 0:
                 log.msg("No shared repo found, creating it")
                 # bzr info fails, try to create shared repo.
-                c = runprocess.RunProcess(self.builder, [self.vcexe, 'init-repo', '.'],
+                c = runprocess.RunProcess(self.builder, [bzr, 'init-repo', '.'],
                                  self.builder.basedir,
                                  sendRC=False, usePTY=False)
                 self.command = c
@@ -145,7 +150,8 @@ def get_revision_number(self, out):
         raise ValueError("unable to find revno: in bzr output: '%s'" % out)
 
     def parseGotRevision(self):
-        command = [self.vcexe, "version-info"]
+        bzr = self.getCommand('bzr')
+        command = [bzr, "version-info"]
         c = runprocess.RunProcess(self.builder, command,
                          os.path.join(self.builder.basedir, self.srcdir),
                          environ=self.env,

slave/buildslave/commands/cvs.py

@@ -26,7 +26,6 @@ class CVS(SourceBaseCommand):
 
     def setup(self, args):
         SourceBaseCommand.setup(self, args)
-        self.vcexe = utils.getCommand("cvs")
         self.cvsroot = args['cvsroot']
         self.cvsmodule = args['cvsmodule']
         self.global_options = args.get('global_options', [])
@@ -44,10 +43,11 @@ def sourcedirIsUpdateable(self):
                                            self.srcdir, "CVS")))
 
     def start(self):
+        cvs = self.getCommand("cvs")
         if self.login is not None:
             # need to do a 'cvs login' command first
             d = self.builder.basedir
-            command = ([self.vcexe, '-d', self.cvsroot] + self.global_options
+            command = ([cvs, '-d', self.cvsroot] + self.global_options
                        + ['login'])
             c = runprocess.RunProcess(self.builder, command, d,
                              sendRC=False, timeout=self.timeout,
@@ -66,8 +66,9 @@ def _didLogin(self, res):
         return SourceBaseCommand.start(self)
 
     def doVCUpdate(self):
+        cvs = self.getCommand("cvs")
         d = os.path.join(self.builder.basedir, self.srcdir)
-        command = [self.vcexe, '-z3'] + self.global_options + ['update', '-dP']
+        command = [cvs, '-z3'] + self.global_options + ['update', '-dP']
         if self.branch:
             command += ['-r', self.branch]
         if self.revision:
@@ -79,12 +80,13 @@ def doVCUpdate(self):
         return c.start()
 
     def doVCFull(self):
+        cvs = self.getCommand("cvs")
         d = self.builder.basedir
         if self.mode == "export":
             verb = "export"
         else:
             verb = "checkout"
-        command = ([self.vcexe, '-d', self.cvsroot, '-z3'] +
+        command = ([cvs, '-d', self.cvsroot, '-z3'] +
                    self.global_options +
                    [verb, '-d', self.srcdir])
 

slave/buildslave/commands/darcs.py

@@ -16,7 +16,6 @@ class Darcs(SourceBaseCommand):
 
     def setup(self, args):
         SourceBaseCommand.setup(self, args)
-        self.vcexe = utils.getCommand("darcs")
         self.repourl = args['repourl']
         self.sourcedata = "%s\n" % self.repourl
         self.revision = self.args.get('revision')
@@ -29,20 +28,22 @@ def sourcedirIsUpdateable(self):
                                            self.srcdir, "_darcs")))
 
     def doVCUpdate(self):
+        darcs = self.getCommand('darcs')
         assert not self.revision
         # update: possible for mode in ('copy', 'update')
         d = os.path.join(self.builder.basedir, self.srcdir)
-        command = [self.vcexe, 'pull', '--all', '--verbose']
+        command = [darcs, 'pull', '--all', '--verbose']
         c = runprocess.RunProcess(self.builder, command, d,
                          sendRC=False, timeout=self.timeout,
                          maxTime=self.maxTime, usePTY=False)
         self.command = c
         return c.start()
 
     def doVCFull(self):
+        darcs = self.getCommand('darcs')
         # checkout or export
         d = self.builder.basedir
-        command = [self.vcexe, 'get', '--verbose', '--partial',
+        command = [darcs, 'get', '--verbose', '--partial',
                    '--repo-name', self.srcdir]
         if self.revision:
             # write the context to a file
@@ -69,8 +70,10 @@ def removeContextFile(self, res, n):
         return res
 
     def parseGotRevision(self):
+        darcs = self.getCommand('darcs')
+
         # we use 'darcs context' to find out what we wound up with
-        command = [self.vcexe, "changes", "--context"]
+        command = [darcs, "changes", "--context"]
         c = runprocess.RunProcess(self.builder, command,
                          os.path.join(self.builder.basedir, self.srcdir),
                          environ=self.env, timeout=self.timeout,

slave/buildslave/commands/git.py

@@ -23,7 +23,6 @@ class Git(SourceBaseCommand):
 
     def setup(self, args):
         SourceBaseCommand.setup(self, args)
-        self.vcexe = utils.getCommand("git")
         self.repourl = args['repourl']
         self.branch = args.get('branch')
         if not self.branch:
@@ -44,7 +43,8 @@ def sourcedirIsUpdateable(self):
         return os.path.isdir(os.path.join(self._fullSrcdir(), ".git"))
 
     def _dovccmd(self, command, cb=None, **kwargs):
-        c = runprocess.RunProcess(self.builder, [self.vcexe] + command, self._fullSrcdir(),
+        git = self.getCommand("git")
+        c = runprocess.RunProcess(self.builder, [git] + command, self._fullSrcdir(),
                          sendRC=False, timeout=self.timeout,
                          maxTime=self.maxTime, usePTY=False, **kwargs)
         self.command = c
@@ -143,10 +143,12 @@ def _didInit(self, res):
         return self.doVCUpdate()
 
     def doVCFull(self):
+        git = self.getCommand("git")
+
         # If they didn't ask for a specific revision, we can get away with a
         # shallow clone.
         if not self.args.get('revision') and self.args.get('shallow'):
-            cmd = [self.vcexe, 'clone', '--depth', '1', self.repourl,
+            cmd = [git, 'clone', '--depth', '1', self.repourl,
                    self._fullSrcdir()]
             c = runprocess.RunProcess(self.builder, cmd, self.builder.basedir,
                              sendRC=False, timeout=self.timeout,

slave/buildslave/commands/hg.py

@@ -20,7 +20,6 @@ class Mercurial(SourceBaseCommand):
 
     def setup(self, args):
         SourceBaseCommand.setup(self, args)
-        self.vcexe = utils.getCommand("hg")
         self.repourl = args['repourl']
         self.clobberOnBranchChange = args.get('clobberOnBranchChange', True)
         self.sourcedata = "%s\n" % self.repourl
@@ -34,8 +33,9 @@ def sourcedirIsUpdateable(self):
                                           self.srcdir, ".hg"))
 
     def doVCUpdate(self):
+        hg = self.getCommand('hg')
         d = os.path.join(self.builder.basedir, self.srcdir)
-        command = [self.vcexe, 'pull', '--verbose', self.repourl]
+        command = [hg, 'pull', '--verbose', self.repourl]
         c = runprocess.RunProcess(self.builder, command, d,
                          sendRC=False, timeout=self.timeout,
                          maxTime=self.maxTime, keepStdout=True, usePTY=False)
@@ -56,7 +56,8 @@ def _handleEmptyUpdate(self, res):
         return res
 
     def doVCFull(self):
-        command = [self.vcexe, 'clone', '--verbose', '--noupdate']
+        hg = self.getCommand('hg')
+        command = [hg, 'clone', '--verbose', '--noupdate']
 
         # if got revision, clobbering and in dirname, only clone to specific revision
         # (otherwise, do full clone to re-use .hg dir for subsequent builds)
@@ -87,8 +88,9 @@ def _vcfull(res):
         return c
 
     def _purge(self, dummy, dirname):
+        hg = self.getCommand('hg')
         d = os.path.join(self.builder.basedir, self.srcdir)
-        purge = [self.vcexe, 'purge', '--all']
+        purge = [hg, 'purge', '--all']
         purgeCmd = runprocess.RunProcess(self.builder, purge, d,
                                 keepStdout=True, keepStderr=True, usePTY=False)
 
@@ -109,14 +111,15 @@ def _clobber(res):
         return p
 
     def _update(self, res):
+        hg = self.getCommand('hg')
         if res != 0:
             return res
 
         # compare current branch to update
         self.update_branch = self.args.get('branch',  'default')
 
         d = os.path.join(self.builder.basedir, self.srcdir)
-        parentscmd = [self.vcexe, 'identify', '--num', '--branch']
+        parentscmd = [hg, 'identify', '--num', '--branch']
         cmd = runprocess.RunProcess(self.builder, parentscmd, d,
                            sendRC=False, timeout=self.timeout, keepStdout=True,
                            keepStderr=True, usePTY=False)
@@ -170,7 +173,8 @@ def _parseIdentify(res):
             return 0
 
         def _checkRepoURL(res):
-            parentscmd = [self.vcexe, 'paths', 'default']
+            hg = self.getCommand('hg')
+            parentscmd = [hg, 'paths', 'default']
             cmd2 = runprocess.RunProcess(self.builder, parentscmd, d,
                                keepStdout=True, keepStderr=True, usePTY=False,
                                timeout=self.timeout, sendRC=False)
@@ -235,7 +239,8 @@ def _vcfull(res):
         return c
 
     def _update2(self, res):
-        updatecmd=[self.vcexe, 'update', '--clean', '--repository', self.srcdir]
+        hg = self.getCommand('hg')
+        updatecmd=[hg, 'update', '--clean', '--repository', self.srcdir]
         if self.args.get('revision'):
             updatecmd.extend(['--rev', self.args['revision']])
         else:
@@ -246,8 +251,9 @@ def _update2(self, res):
         return self.command.start()
 
     def parseGotRevision(self):
+        hg = self.getCommand('hg')
         # we use 'hg identify' to find out what we wound up with
-        command = [self.vcexe, "identify", "--id", "--debug"] # get full rev id
+        command = [hg, "identify", "--id", "--debug"] # get full rev id
         c = runprocess.RunProcess(self.builder, command,
                          os.path.join(self.builder.basedir, self.srcdir),
                          environ=self.env, timeout=self.timeout,