наброски.py

#!/usr/bin/python
import os
import sys
import subprocess


def _bfs_paths(structure, start, goal):
    queue = [(start, [start])]
    while queue:
        (vertex, path) = queue.pop(0)
        if vertex not in structure:
            continue
        remaining_paths = set(structure[vertex].keys()) - set(path)
        for next_value in remaining_paths:
            if next_value == goal:
                yield path + [next_value]
            else:
                queue.append((next_value, path + [next_value]))


def _convert2filelist(structure, path):
    return [structure[path[i]][path[i+1]] for i in range(len(path)-1)]


def _build_graph(creation_path, migration_path):
    result = {None:{}}
    for root, dirs, fileset in os.walk(creation_path):
        for next_file in fileset:
            if next_file.endswith(".sql"):
                full_path = os.path.join(root, next_file)
                b = next_file.replace(".sql", "")
                result[None][b] = full_path

    for root, dirs, fileset in os.walk(migration_path):
        for next_file in fileset:
            if next_file.endswith(".sql"):
                full_path = os.path.join(root, next_file)
                wire = next_file.replace(".sql", "").split("to")
                a = wire[0]
                b = wire[1]
                if a in result.keys():
                    result[a][b] = full_path
                else:
                    result[a] = {b: full_path}
    return result


def shortest_path(creation_path, migration_path, start, goal):
    graph = _build_graph(creation_path, migration_path)
    if start == goal:
        sys.stderr.write("INFO : Scheme version is %s already, skipping\n" % (start))
        return
    for path in _bfs_paths(graph, start, goal):
        sys.stderr.write("INFO : Yielding list: %s\n" % (path))
        file_list = _convert2filelist(graph, path)
        yield file_list
    sys.stderr.write("ERROR: There is no any other " +
                     "possible paths from %s to %s!\n" % (start, goal))


class Psql:
    def __init__(self,  username, password="", params = [],  psql = "psql"):
        self.username = username
        self.password = password
        self.params   = params
        self.psql     = psql

    def execute_command(self, params):
        try:
            call = [self.psql] + params + self.params
            print(call)
            stdout = subprocess.check_output(call, env={"PGPASSWORD":self.password, "PGUSER":self.username})
            return 0, stdout
        except subprocess.CalledProcessError as e:
            return e.returncode, e.output

    def get_db_version(self, dbname):
        errcode, output = self.execute_command(
            ["-d", dbname, "-qc", "copy (select id from version) to stdout;"])

        if errcode == 0:
            return output
        else:
            sys.stderr.write("System returned this:" + output)
            sys.stderr.write("There is no db scheme at all")
            return None

    def is_db_exists(self, dbname):
        errcode, output = self.execute_command(["-lqtA"])
        if errcode != 0:
            # TODO Throw some error
            return False

        for line in output.splitlines():
            dbname_ = line.split("|")[0] # Get table name exactly
            if dbname_ == dbname:
                return True
        return False

# The actual code starts here
if __name__ == "__main__":
    """
    :arg path to creation sql scripts
    :arg path to migration sql scripts, each of which must have name '{before}to{after}.sql'
         where before - version of scheme before, and after - ver of scheme after that
         migration script
    :arg desired version of db scheme
    """
    dbname = "overseer"

    instance = Psql('overseer', 'overseer', ['-h', 'localhost'])

    current = None
    if instance.is_db_exists(dbname):
        current = instance.get_db_version(dbname)
    for filelist in shortest_path(sys.argv[1], sys.argv[2], current, sys.argv[3]):
        err = 0
        for file in filelist:
            err, output = instance.execute_command(["--single-transaction", "-f", file])
            if err != 0:
                break
        if err != 0:
            break