diff options
| -rw-r--r-- | lib/spack/spack/spec.py | 31 | ||||
| -rw-r--r-- | lib/spack/spack/test/spec_dag.py | 34 |
2 files changed, 61 insertions, 4 deletions
diff --git a/lib/spack/spack/spec.py b/lib/spack/spack/spec.py index ba9cea876d..94ac8788ba 100644 --- a/lib/spack/spack/spec.py +++ b/lib/spack/spack/spec.py @@ -963,13 +963,10 @@ class Spec(object): return Prefix(spack.install_layout.path_for_spec(self)) def dag_hash(self, length=None): - """ - Return a hash of the entire spec DAG, including connectivity. - """ + """Return a hash of the entire spec DAG, including connectivity.""" if self._hash: return self._hash[:length] else: - # XXX(deptype): ignore 'build' dependencies here yaml_text = syaml.dump( self.to_node_dict(), default_flow_style=True, width=sys.maxint) sha = hashlib.sha1(yaml_text) @@ -978,6 +975,10 @@ class Spec(object): self._hash = b32_hash return b32_hash + def dag_hash_bit_prefix(self, bits): + """Get the first <bits> bits of the DAG hash as an integer type.""" + return base32_prefix_bits(self.dag_hash(), bits) + def to_node_dict(self): d = syaml_dict() @@ -999,6 +1000,8 @@ class Spec(object): if self.architecture: d['arch'] = self.architecture.to_dict() + # TODO: restore build dependencies here once we have less picky + # TODO: concretization. deps = self.dependencies_dict(deptype=('link', 'run')) if deps: d['dependencies'] = syaml_dict([ @@ -2723,6 +2726,26 @@ def parse_anonymous_spec(spec_like, pkg_name): return anon_spec +def base32_prefix_bits(hash_string, bits): + """Return the first <bits> bits of a base32 string as an integer.""" + if bits > len(hash_string) * 5: + raise ValueError("Too many bits! Requested %d bit prefix of '%s'." + % (bits, hash_string)) + + hash_bytes = base64.b32decode(hash_string, casefold=True) + + result = 0 + n = 0 + for i, b in enumerate(hash_bytes): + n += 8 + result = (result << 8) | ord(b) + if n >= bits: + break + + result >>= (n - bits) + return result + + class SpecError(spack.error.SpackError): """Superclass for all errors that occur while constructing specs.""" diff --git a/lib/spack/spack/test/spec_dag.py b/lib/spack/spack/test/spec_dag.py index 40cdb02966..0bc63bcf0f 100644 --- a/lib/spack/spack/test/spec_dag.py +++ b/lib/spack/spack/test/spec_dag.py @@ -523,3 +523,37 @@ class SpecDagTest(MockPackagesTest): level = descend_and_check(dag.to_node_dict()) # level just makes sure we are doing something here self.assertTrue(level >= 5) + + def test_hash_bits(self): + """Ensure getting first n bits of a base32-encoded DAG hash works.""" + + # RFC 4648 base32 decode table + b32 = dict((j, i) for i, j in enumerate('abcdefghijklmnopqrstuvwxyz')) + b32.update(dict((j, i) for i, j in enumerate('234567', 26))) + + # some package hashes + tests = [ + '35orsd4cenv743hg4i5vxha2lzayycby', + '6kfqtj7dap3773rxog6kkmoweix5gpwo', + 'e6h6ff3uvmjbq3azik2ckr6ckwm3depv', + 'snz2juf4ij7sv77cq3vs467q6acftmur', + '4eg47oedi5bbkhpoxw26v3oe6vamkfd7', + 'vrwabwj6umeb5vjw6flx2rnft3j457rw'] + + for test_hash in tests: + # string containing raw bits of hash ('1' and '0') + expected = ''.join([format(b32[c], '#07b').replace('0b', '') + for c in test_hash]) + + for bits in (1, 2, 3, 4, 7, 8, 9, 16, 64, 117, 128, 160): + actual_int = spack.spec.base32_prefix_bits(test_hash, bits) + fmt = "#0%sb" % (bits + 2) + actual = format(actual_int, fmt).replace('0b', '') + + self.assertEqual(expected[:bits], actual) + + self.assertRaises( + ValueError, spack.spec.base32_prefix_bits, test_hash, 161) + + self.assertRaises( + ValueError, spack.spec.base32_prefix_bits, test_hash, 256) |