Consolidate some web-spidering commands in spack.util.web

- move `spack.cmd.checksum.get_checksums` to `spack.util.web.spider_checksums`

- move `spack.error.NoNetworkError` to `spack.util.web.NoNetworkError` since
  it is only used there.

6 files changed, 118 insertions, 116 deletions

diff --git a/lib/spack/spack/cmd/checksum.py b/lib/spack/spack/cmd/checksum.py
index 0d56f971c8..e19eb540a8 100644
--- a/lib/spack/spack/cmd/checksum.py
+++ b/lib/spack/spack/cmd/checksum.py
@@ -25,13 +25,12 @@
 from __future__ import print_function
 
 import argparse
-import hashlib
 
 import llnl.util.tty as tty
 import spack
 import spack.cmd
 import spack.util.crypto
-from spack.stage import Stage, FailedDownloadError
+import spack.util.web
 from spack.util.naming import *
 from spack.version import *
 
@@ -52,90 +51,6 @@ def setup_parser(subparser):
         help='versions to generate checksums for')
 
 
-def get_checksums(url_dict, name, **kwargs):
-    """Fetches and checksums archives from URLs.
-
-    This function is called by both ``spack checksum`` and ``spack create``.
-    The ``first_stage_function`` kwarg allows ``spack create`` to determine
-    things like the build system of the archive.
-
-    Args:
-        url_dict (dict): A dictionary of the form: version -> URL
-        name (str): The name of the package
-        first_stage_function (callable): Function to run on first staging area
-        keep_stage (bool): Don't clean up staging area when command completes
-
-    Returns:
-        str: A multi-line string containing versions and corresponding hashes
-    """
-    first_stage_function = kwargs.get('first_stage_function', None)
-    keep_stage = kwargs.get('keep_stage', False)
-
-    sorted_versions = sorted(url_dict.keys(), reverse=True)
-
-    # Find length of longest string in the list for padding
-    max_len = max(len(str(v)) for v in sorted_versions)
-    num_ver = len(sorted_versions)
-
-    tty.msg("Found {0} version{1} of {2}:".format(
-            num_ver, '' if num_ver == 1 else 's', name),
-            "",
-            *spack.cmd.elide_list(
-                ["{0:{1}}  {2}".format(str(v), max_len, url_dict[v])
-                 for v in sorted_versions]))
-    print()
-
-    archives_to_fetch = tty.get_number(
-        "How many would you like to checksum?", default=1, abort='q')
-
-    if not archives_to_fetch:
-        tty.die("Aborted.")
-
-    versions = sorted_versions[:archives_to_fetch]
-    urls = [url_dict[v] for v in versions]
-
-    tty.msg("Downloading...")
-    version_hashes = []
-    i = 0
-    for url, version in zip(urls, versions):
-        try:
-            with Stage(url, keep=keep_stage) as stage:
-                # Fetch the archive
-                stage.fetch()
-                if i == 0 and first_stage_function:
-                    # Only run first_stage_function the first time,
-                    # no need to run it every time
-                    first_stage_function(stage, url)
-
-                # Checksum the archive and add it to the list
-                version_hashes.append((version, spack.util.crypto.checksum(
-                    hashlib.md5, stage.archive_file)))
-                i += 1
-        except FailedDownloadError:
-            tty.msg("Failed to fetch {0}".format(url))
-        except Exception as e:
-            tty.msg("Something failed on {0}, skipping.".format(url),
-                    "  ({0})".format(e))
-
-    if not version_hashes:
-        tty.die("Could not fetch any versions for {0}".format(name))
-
-    # Find length of longest string in the list for padding
-    max_len = max(len(str(v)) for v, h in version_hashes)
-
-    # Generate the version directives to put in a package.py
-    version_lines = "\n".join([
-        "    version('{0}', {1}'{2}')".format(
-            v, ' ' * (max_len - len(str(v))), h) for v, h in version_hashes
-    ])
-
-    num_hash = len(version_hashes)
-    tty.msg("Checksummed {0} version{1} of {2}".format(
-        num_hash, '' if num_hash == 1 else 's', name))
-
-    return version_lines
-
-
 def checksum(parser, args):
     # Make sure the user provided a package and not a URL
     if not valid_fully_qualified_module_name(args.package):
@@ -160,7 +75,7 @@ def checksum(parser, args):
         if not url_dict:
             tty.die("Could not find any versions for {0}".format(pkg.name))
 
-    version_lines = get_checksums(
+    version_lines = spack.util.web.get_checksums_for_versions(
         url_dict, pkg.name, keep_stage=args.keep_stage)
 
     print()
diff --git a/lib/spack/spack/cmd/create.py b/lib/spack/spack/cmd/create.py
index 29f888fd59..fd755facac 100644
--- a/lib/spack/spack/cmd/create.py
+++ b/lib/spack/spack/cmd/create.py
@@ -30,7 +30,6 @@ import re
 import llnl.util.tty as tty
 import spack
 import spack.cmd
-import spack.cmd.checksum
 import spack.util.web
 from llnl.util.filesystem import mkdirp
 from spack.repository import Repo
@@ -587,7 +586,7 @@ def get_versions(args, name):
             version = parse_version(args.url)
             url_dict = {version: args.url}
 
-        versions = spack.cmd.checksum.get_checksums(
+        versions = spack.util.web.get_checksums_for_versions(
             url_dict, name, first_stage_function=guesser,
             keep_stage=args.keep_stage)
 
diff --git a/lib/spack/spack/error.py b/lib/spack/spack/error.py
index 645864822f..534425b0ad 100644
--- a/lib/spack/spack/error.py
+++ b/lib/spack/spack/error.py
@@ -113,16 +113,6 @@ class UnsupportedPlatformError(SpackError):
         super(UnsupportedPlatformError, self).__init__(message)
 
 
-class NoNetworkConnectionError(SpackError):
-    """Raised when an operation needs an internet connection."""
-
-    def __init__(self, message, url):
-        super(NoNetworkConnectionError, self).__init__(
-            "No network connection: " + str(message),
-            "URL was: " + str(url))
-        self.url = url
-
-
 class SpecError(SpackError):
     """Superclass for all errors that occur while constructing specs."""
 
diff --git a/lib/spack/spack/fetch_strategy.py b/lib/spack/spack/fetch_strategy.py
index e140579d2c..bc9030ba8c 100644
--- a/lib/spack/spack/fetch_strategy.py
+++ b/lib/spack/spack/fetch_strategy.py
@@ -54,13 +54,14 @@ from llnl.util.filesystem import *
 import spack
 import spack.error
 import spack.util.crypto as crypto
+import spack.util.pattern as pattern
 from spack.util.executable import *
 from spack.util.string import *
 from spack.version import Version, ver
 from spack.util.compression import decompressor_for, extension
 
-import spack.util.pattern as pattern
-"""List of all fetch strategies, created by FetchStrategy metaclass."""
+
+#: List of all fetch strategies, created by FetchStrategy metaclass.
 all_strategies = []
 
 
@@ -967,7 +968,7 @@ def from_list_url(pkg):
        the specified package's version."""
     if pkg.list_url:
         try:
-            versions = pkg.fetch_remote_versions()
+            versions = pkg.fetch_remote_package_versions()
             try:
                 url_from_list = versions[pkg.version]
                 digest = None
diff --git a/lib/spack/spack/package.py b/lib/spack/spack/package.py
index 0bebb48387..1c722082e8 100644
--- a/lib/spack/spack/package.py
+++ b/lib/spack/spack/package.py
@@ -1841,7 +1841,7 @@ class PackageBase(with_metaclass(PackageMeta, object)):
         try:
             return spack.util.web.find_versions_of_archive(
                 self.all_urls, self.list_url, self.list_depth)
-        except spack.error.NoNetworkConnectionError as e:
+        except spack.util.web.NoNetworkConnectionError as e:
             tty.die("Package.fetch_versions couldn't connect to:", e.url,
                     e.message)
 
@@ -2064,15 +2064,6 @@ class PackageVersionError(PackageError):
             "Please provide a url for this version in the package.py file.")
 
 
-class VersionFetchError(PackageError):
-    """Raised when a version URL cannot automatically be determined."""
-
-    def __init__(self, cls):
-        super(VersionFetchError, self).__init__(
-            "Cannot fetch versions for package %s " % cls.__name__ +
-            "because it does not define any URLs to fetch.")
-
-
 class NoURLError(PackageError):
     """Raised when someone tries to build a URL for a package with no URLs."""
 
diff --git a/lib/spack/spack/util/web.py b/lib/spack/spack/util/web.py
index 842a3db07e..a1944b8d65 100644
--- a/lib/spack/spack/util/web.py
+++ b/lib/spack/spack/util/web.py
@@ -22,11 +22,14 @@
 # License along with this program; if not, write to the Free Software
 # Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 ##############################################################################
+from __future__ import print_function
+
 import re
 import os
 import ssl
 import sys
 import traceback
+import hashlib
 
 from six.moves.urllib.request import urlopen, Request
 from six.moves.urllib.error import URLError
@@ -50,8 +53,9 @@ import spack
 import spack.error
 from spack.util.compression import ALLOWED_ARCHIVE_TYPES
 
+
 # Timeout in seconds for web requests
-TIMEOUT = 10
+_timeout = 10
 
 
 class LinkParser(HTMLParser):
@@ -127,7 +131,7 @@ def _spider(url, visited, root, depth, max_depth, raise_on_error):
         # if you ask for a tarball with Accept: text/html.
         req = Request(url)
         req.get_method = lambda: "HEAD"
-        resp = _urlopen(req, timeout=TIMEOUT, context=context)
+        resp = _urlopen(req, timeout=_timeout, context=context)
 
         if "Content-type" not in resp.headers:
             tty.debug("ignoring page " + url)
@@ -140,7 +144,7 @@ def _spider(url, visited, root, depth, max_depth, raise_on_error):
 
         # Do the real GET request when we know it's just HTML.
         req.get_method = lambda: "GET"
-        response = _urlopen(req, timeout=TIMEOUT, context=context)
+        response = _urlopen(req, timeout=_timeout, context=context)
         response_url = response.geturl()
 
         # Read the page and and stick it in the map we'll return
@@ -199,7 +203,7 @@ def _spider(url, visited, root, depth, max_depth, raise_on_error):
                      "own risk.")
 
         if raise_on_error:
-            raise spack.error.NoNetworkConnectionError(str(e), url)
+            raise NoNetworkConnectionError(str(e), url)
 
     except HTMLParseError as e:
         # This error indicates that Python's HTML parser sucks.
@@ -328,3 +332,105 @@ def find_versions_of_archive(archive_urls, list_url=None, list_depth=0):
                 continue
 
     return versions
+
+
+def get_checksums_for_versions(
+        url_dict, name, first_stage_function=None, keep_stage=False):
+    """Fetches and checksums archives from URLs.
+
+    This function is called by both ``spack checksum`` and ``spack
+    create``.  The ``first_stage_function`` argument allows the caller to
+    inspect the first downloaded archive, e.g., to determine the build
+    system.
+
+    Args:
+        url_dict (dict): A dictionary of the form: version -> URL
+        name (str): The name of the package
+        first_stage_function (callable): function that takes a Stage and a URL;
+            this is run on the stage of the first URL downloaded
+        keep_stage (bool): whether to keep staging area when command completes
+
+    Returns:
+        (str): A multi-line string containing versions and corresponding hashes
+
+    """
+    sorted_versions = sorted(url_dict.keys(), reverse=True)
+
+    # Find length of longest string in the list for padding
+    max_len = max(len(str(v)) for v in sorted_versions)
+    num_ver = len(sorted_versions)
+
+    tty.msg("Found {0} version{1} of {2}:".format(
+            num_ver, '' if num_ver == 1 else 's', name),
+            "",
+            *spack.cmd.elide_list(
+                ["{0:{1}}  {2}".format(str(v), max_len, url_dict[v])
+                 for v in sorted_versions]))
+    print()
+
+    archives_to_fetch = tty.get_number(
+        "How many would you like to checksum?", default=1, abort='q')
+
+    if not archives_to_fetch:
+        tty.die("Aborted.")
+
+    versions = sorted_versions[:archives_to_fetch]
+    urls = [url_dict[v] for v in versions]
+
+    tty.msg("Downloading...")
+    version_hashes = []
+    i = 0
+    for url, version in zip(urls, versions):
+        try:
+            with spack.stage.Stage(url, keep=keep_stage) as stage:
+                # Fetch the archive
+                stage.fetch()
+                if i == 0 and first_stage_function:
+                    # Only run first_stage_function the first time,
+                    # no need to run it every time
+                    first_stage_function(stage, url)
+
+                # Checksum the archive and add it to the list
+                version_hashes.append((version, spack.util.crypto.checksum(
+                    hashlib.md5, stage.archive_file)))
+                i += 1
+        except spack.stage.FailedDownloadError:
+            tty.msg("Failed to fetch {0}".format(url))
+        except Exception as e:
+            tty.msg("Something failed on {0}, skipping.".format(url),
+                    "  ({0})".format(e))
+
+    if not version_hashes:
+        tty.die("Could not fetch any versions for {0}".format(name))
+
+    # Find length of longest string in the list for padding
+    max_len = max(len(str(v)) for v, h in version_hashes)
+
+    # Generate the version directives to put in a package.py
+    version_lines = "\n".join([
+        "    version('{0}', {1}'{2}')".format(
+            v, ' ' * (max_len - len(str(v))), h) for v, h in version_hashes
+    ])
+
+    num_hash = len(version_hashes)
+    tty.msg("Checksummed {0} version{1} of {2}".format(
+        num_hash, '' if num_hash == 1 else 's', name))
+
+    return version_lines
+
+
+class SpackWebError(spack.error.SpackError):
+    """Superclass for Spack web spidering errors."""
+
+
+class VersionFetchError(SpackWebError):
+    """Raised when we can't determine a URL to fetch a package."""
+
+
+class NoNetworkConnectionError(SpackWebError):
+    """Raised when an operation can't get an internet connection."""
+    def __init__(self, message, url):
+        super(NoNetworkConnectionError, self).__init__(
+            "No network connection: " + str(message),
+            "URL was: " + str(url))
+        self.url = url